Silicon and Germanium

1) Carbon: kolefni
1) diamond: alsverfir (scratches all other substances because it is the hardest stone), kóngasteinn (king of stones, most noble gem), þolefni (pun on kolefni)
2) graphite: ritkol, ritblý
3) graphene: netkol

2) Silicon: synonyms for kísill could be: sandkol, sendi (the carbon in "sand" (= SiO2) jarðmálmungur (the earth-metalloid, most abundant metalloid in the earths crust), frummálmungur (the first metalloid to be formed in the universe, boron was formed afterwards in a process called "cosmic ray spallation".

3) Germanium
1) blendiskísill:
In the same way as the word "salt" in it's original and narrowest meaning designates NaCl, the German mineralogical term "blende" denotes "sphalerite" or "zinkblende" (zinc sulphide, ZnS), the most well-known of the "blendes". The English name of the mineral "sphalerite" derives from Greek "sphaleros", treacherous, and is semantically equivalent with the German "blende", which was coined by Agricola in 1546, and is from the derived from "blenden" (to blind, or deceive), because the mineral resembles lead-ore in appearance but contains no lead, and was consequently oftep rejected as worthless . Today, germanium is mined primarily from sphalerite (the primary ore of zinc), though germanium is also recovered commercially from silver, lead, and copper ores.  See http://en.wikipedia.org/wiki/Germanium
For that reason, one could call germanium "blendiskísill" (the "silicon" from sphalerite)
2) þýskakísli: This is a funny sounding word, which we call "tickle-words" (kietelwoorden) in Dutch, like "kanunnikenkapittel", which translates as "kanúkakapitúli" and I have a feeling this word rolls from the native Icelandic tongue as sweetly and smoothly as in the case of the originally Dutch construction. Maybe the average sense of humor of the "market", as Icelandic terminologists call the general public with regard to the acceptance of newly-coined words, will help to get this one through, who knows?
3) hálftin: The prefix ‘hálf’ refers on the one hand to the semimetallic properties of germanium and on the other to its being situated exactly in the middle between silicon and tin. In this latter sense the prefix is used in the same way as hálf- in hálfþrítugur. The prefix perfectly denotes its intermediate position, being chemically homologous with silicon and tin.

alkali metals (lútarmálmar, votbrennimálmar)

There are many possibilities to translate the term alkalimetal
1) illmálmar (opposite of góðmálmar (noble metals). Alkali metals are the most reactive which means they are the opposite of the noble metals.
2) lútarmálmur (lye-metal)
3) votbrennimálmur (wet-burning metals): Alkalimetals react violently with water, especially the heavier ones like Rubidium and Cesium. Although this is a property also observed in heavier alkaline earth elements like barium and radium, compared to the alkalimetals the effect is much less, so we can reserve the term "wet-burning metals" for the alkalimetals. I liked the term because of the funny pseudocontradiction: normally water is seen as a fire-extinguisher, except when it meets with an alkali metal.
4) vítismálmur (from "vítissóti", the corrosive natrium oxide.  Víti (hell) is a good reference to the fact that alkali metals react violently upon contact with water and spontaneously burn in air.)

1) Lithium:

1) melmlingur: (diminutive of málmur (metal)). The most obvious property of lithium is its being the lightest of all metallic elements and the small size of its ion Li+, which makes it valuable in dry batteries.  Compounds with superlatives like léttastimálmur, alas, sound clumsy. There is hæstiréttur, yes, but these constructions seems to be exceptions to the rule. Generally, superlatives in compounds is seldomely seen in terminology, which I can fully comprehend.  When I tried out these compounds in Dutch, they sound clumsy too.

I happened to find a website where the lightness of lithium is compared to a "baby":

 

Mercury is like the 200 pound bully attacking a 7 pound baby; the small baby doesn't have much of a chance. 200 and 7 are the molecular weights of mercury (the bully) and lithium (the baby) respectively. If you have been diagnosed with bipolar depression, maybe what you need is less mercury, not more lithium pills. http://www.drkaslow.com/html/mercury_s_influence.html

 

2) laufsteinsmálmur, laufspatsmálmur, laufspeti : it actually turned out to be possible to create an extremely pure and still relatively short compound to designate the element lithium.  It's a word that consists of three words from Icelandic core vocabulary, like þórþungsteinn for uranium: laufsteinsmálmur, no mistake. Just answer the following question: What metallic element was first found in a mineral named after "leaves": I went through the periodic system, it's lithium, no mistake.  Lithium was first discovered in petallite (laufspat) and which still is one of the most important sources of the metal.  Not so many minerals are named after leaves  http://www.peterharben.com/pwhimname.html , but in order to avoid confusion I thought that "spat" as a second element would specify the mineral more so that connotations can be avoided.  First I want to say that I don't have a problem with the germanism "spat", it is well adapted, but if there is a possibility to make an even purer and more elegant Icelandic neologism from the hyperpurely Icelandic core-vocabulary, I choose the latter way. It is possible to hyponymize laufspat to laufsteinn to refer to petallite when creating a word for the metal because the latter part málmur (metal) has a semanticly modulating effect on the first part laufsteinn, as it renders the need to explicitely refer to  the spathic nature of stone superfluous.  The compound Laufsteinn in laufsteinsmálmur can't refer to anything else than the mineral petallite because no other metallic element is named after a mineral that is in its turn named after leaves, not any, so that's good news.  That doesn't mean that 'laufspat" can be used for the mineral.  In English, some minerals have 5 different names.

Another advantage of using "laufsteinn" is that "steinn" is a literal translation of the Greek "lithos".  
Lithium is an element that is rare in the universe.  Because its nucleus desintegrates at temperatures higher than 2.5 million K, most of the primordial lithium is destroyed and like the element 4 and 5 beryllium and boron, they are mostly formed in the cold interstellar space as a result of the collision of cosmic ray particles that collide at relativistic velocities with nuclei of heavier elements. 
It's a wonder that an element so unabundant, terrestrially as well as cosmicly can be given a name as relatively short as laufsteinsmálmur.

3) geðmálmur (Lithium salts have a remarkable ability to affect the mind by altering the chemical state of nerve cells in the brain. The carbonate and acetate are prescribed for manic depression and help to limit the extremes of mental state that are a feature of this condition, the sulfate and chloride are more often prescribed as straight anti-depressants and the bromide finds use as a sedative. Lithium could has well have been called "psychium". No other metallic element exhibits this property of affecting the mind (with anything any more complex than its simplest salts) as lithium does. 
In the treatment of bipolar disorder, lithium compounds continue to be the standard against which newer medications are measured. Lithium salts may also be helpful for related diagnoses, such as schizoaffective disorder and cyclic major depression. The active principle in these salts is the lithium ion Li+, although detailed mechanisms are debated. (see: http://en.wikipedia.org/wiki/Lithium )
On the website "elementymology and elements multidictionary", a unique website about the names of the chemical elements in almost 100 languages, created by the Dutch map historian Peter van der Krogt, there's a list of alternative names for the chemical elements created by the pupils of the Dorseyville Middle school http://www.vanderkrogt.net/elements/dms.php .  I must say that the list was by no means impressive.  Many names look like being created "between the entréé and the main course", as we say in Flemish. Some names were interesting though.  In the list, lithium was called "happiness", which shows that people tend to associate the element preferably with the psychopharmaceutical effects of its simple salts, a property in which lithium is superior to all other metallic elements. In the treatment of bipolar disorder for instance, lithium compounds continue, even now, in the 21th century, to be the standard against which newer medications are measured. It is crystal-clear that this particular property sets lithium so far apart from other metallic elements that the endeavor to express this in a alternative name is fully justified. As for the word's construction, my personal favourite is the compound geðmálmur, which has the same "consonantal lattice" as góðmálmur (noble metal), so I assume it will therefore sound a bit less outlandish than sálmálmur or glaðmálmur, which I coined after glaðloft or glaðgas, a synonym of hláturgas (N2O), nitrous oxide).
The erroneousness of frummálmur (primordial metal): Lithium, along with hydrogen and helium, indeed were formed in the Big Bang event and since there has been consensus to exclude hydrogen, despite its metallic properties when solid, from the list of metals.  This doesn't mean that "frummálmur" is a correct name.  The reason is the following:
During the first gigayear after the Big Bang, most of the primordial lithium was destroyed in the core of the first stars, which were mostly short-lived supergiants that violently ended their lives as supernovae. Now, lithium nuclei desintegrate when the temperature exceeds 2.4 million K, which is too low to survive the inferno of the first giant stars' interior.  Most of the lithium we find in nature was formed after all other elements were formed through stellar fusion or neutron absorption in supernova events. The bulk of the present-day lithium was formed in cold interstellar space by a process called "spallation".  When particles in cosmic rays, travelling thorugh space at relativistic velocities come into collision with nuclei of heavier elements, a lithium nucleus is occasionly chopped off.  So if you look at a bottle containing pure lithium metal, submerged in oil, you may be sure that only a very tiny fraction of it is primordial, while the rest is just the opposite. This makes a term like frummálmur as a designation for lithium inappropriate.


2) sodium
1) sæmálmur (a translation of the Maori name for the element: konutae (konu-prefix denoting a metal) + tae (sea).  http://www.vanderkrogt.net/elements/language.php?language=mi This makes sense as sodium is the most abundant element in sea-water where it is bound to chlorine as salt (NaCl), which explains the older name for hydrochloric acid: "marine acid" (sæsýra).  In the same way, sodium can be designated as "the marine metal". Some might consider the compound "saltmálmur", but this one is actually less correct than the loan-translation from Maori, despite the fact that "salt" in its original, narrowest sense, designates NaCl. In chemical terminology "salt" has has develloped into a term denoting a specific kind of compounds, which makes a term like "sea-metal" much more appropriate a designation than "salt-metal".
3) sótamálmur (from vítissóti, sóti (NaOH, sodium hydroxide (sæmálmsvetnildi)) is also possible, but it contains the loa-word "sóti", so after all it is better to stick with the shorter and purer sæmálmur

3) potassium
1) öskumálmur: Kalium and "kali" in "alkali" mean "ash" in Arabic, not pot-ash, just ash, so the addition of "pottur" isn't necessary. Another example that shows it is possible to omit "pottur" is a German alternative term for "potash": aschensalz (ash-salt).  Therefore I believe that "öskumálmur" would be transparent enough a designation for kalium for an Icelandic chemist.
2) eski (from "aska", like vetni (hydrogen) from vatn (water), ildi (oxygen) from eldur (fire))
3) andeir (anti copper: The alkali metals are chemically the opposite of the noble metals. Alkali metals make up group 1A, while copper silver and gold make up group 1B.  Potassium lies on the same period as "copper (Cu)": andeir, rubidium (Rb) lies on the same period as silver (andsilfur) and cesium (Cs), the most unnoble metal (yes, paradoxically enough more electropositive and reactive than its heavier and illusive brother Francium (Fr) (see under Cesium)) we can call "andgull".

Rubidium:
1) andsilfur, lútarsilfur ("Lútareir" is an incappropriate designation for potassium, because it doesn't explicitely get rid of the idea of a "red metal, while "andeir" denotes a metal that doesn't have to have the same colour as copper.)
2) rófroðamálmur (Four elements were named after the colour of their emission spectrum: Cesium (blue), thallium (green), indium (indigo), and rubidium (deep red). 
http://www.ehow.com/info_12055449_elements-periodic-table-named-colors-emit-burned.html
We can make a construction with róf- (from litróf, occuring uncompounded with -litur (colour) in rófsjá (spectroscope), rófgreining (spectroscôpic analysis).  The compound rófróði (spectral red) can be used to isolate rubidium, the only element named after a "red colour in its emission spectrum is rubidium: rófroðamálmur, not a short word, but not exaggeratedly long either.
Compounds:
Rubidium perchlorate: hábleikiloftssúr rófroðamálmur (or hágallreykssúrt lútarsilfur)
Rubidium iodide: rófróðamálmsþengi (þengi = iodine, from þang, sea-weed)
Rubidium nitrate: saltpéturssúr rófroðumálmur
Rubidium telluride: kóngamálmungi bundinn rofróðumálmur (kóngamálmungur, because tellurium is the only non-metallic element, in this case a metalloid (málmungur) that forms compounds with "gold" the king of metals, in nature (compare to the fact that aqua regia (kóngavatn), was so-called because it dissolved "gold".
http://is.wikipedia.org/wiki/Málmungur

Cesium:
1) andgull (the most unnoble (ironically golden-coloured) metal on the same period as gold, but in group 1A instead of 1B). Gold and cesium don't just have their colours and oxidation states in common but both are monoisotopic elements too).
2) þeygull (the thawing gold, having a melting point of 27°C) see https://www.youtube.com/watch?v=GDMUb5mQsjo
3) hvellgull (the explosive golden-coloured metal)



Francium:
stundarmálmur (The element's most stable isotope has a half-life of no more than 22 minutes, that means that one eighth part of it is still there after an hour, so the compound stundarmálmur, with the first part "stund", interpreted in an additional sense of "klukkustund" (hour), is applicable in this case.)

Earth-alkaline elements (beiskjörðungar, lútjörðungar)

For the Icelandic version of the term "earth alkaline elements" my personal favourites are beinsækinmálmar or beinsækningar (osteophilic metals, osteophilics), beiskjörðungar, beiskjarðarmálmar (bitter (alkaline, think of beiskjuefni, "alkaloid") earths), lútjörðungar, lútjarðarmálmar (lye-earths) or kelkingar (derived from kelki (calcium)).  The term "bitter earth" is an old name for magnesium oxide (MgO), but actually it would make a perfect term to designate the natural oxides of ALL members of the group.  In Icelandic beiskja (bitter) and beiskjuefni is used in the meaning of "alkaloid", and accurately so, for "bitter" is the opposite of "acidic".  For magnesium oxide itself, tálgujörð, þveljujörð or even kléjörð or are possible constructions.

Names of the alkaline earth metals:
1) einsætlingsefni, einsætla (Beryllium is the "lightest element having but one isotope" or the "dwarf of the monoisotopic elements": http://en.wikipedia.org/wiki/Monoisotopic_element
It is possible to found a term upon the icelandic samsæta (isotope). The first step is coining an equivalent of the adjective "monoisotopic", which denotes elements that have but one stable isotope, like beryllium. The Orðabanki íslenskrar málstöðvar doesn't contain an equivalent for the term "monoisotopic element" yet, and my first guess was something like "einsamsætu-". But this might well be reduced to simply einsætu-, judging from the shortening of "monoisotopic" into the more flexible term monotopic in some sources: http://chemwiki.ucdavis.edu/@api/deki/pages/7959/pdf
This convinces me of the accuracy of a construction like einsæta, einsætu-. The term monoisotope is used to designate the isotope of a monoisotopic element (google "is a monoisotope"(between brackets!)). This Pdf-file even contains the word monotope:
http://homepages.rpi.edu/~danony/Papers/Neutron%20Cap%20and%20Trans%20of%20Nb.pdf
"Since natural niobium is a monotope, all of the niobium was 93-Nb".

The literal translation of this "monotope" is einsæta: "Málmynja (Mn), feðginasilfur (Nb), illmálmungur (As), lýsill (P), þengi (I), dyrgi (Co) og lútargull (Cs) eru einsætur."

Beryllium is the "hermit of the spallation triad" (einsetuefni í splundrunarþrennd)", because the other two, lithium and boron, have more than 1 isotope. The "spallation triad" or the "rare lights", as they were called on this webpage http://168.144.87.33/~conworld/cwbb/viewtopic.php?t=942&sid=3129e708fe8d7c361795a74d814ee0e1 , are the three dwarf elements (two metals and a metalloid), that are formed in an extrastellar spallation process because their nuclei can't survive the temperature generated in the core of stars,

One could the diminutive suffix -la (as in pípla) and form einsætla, einsætlingsefni (the "little monotope" or the "dwarf-monotope" or einsetluefni, the "dwarf-hermit of the periodic system"). The name for the element itself can be formed on addition of "málmur" (metal)), which gives the construction: einsætlingsmálmur or einsetlumálmur, but reduced forms einsætlingur or einsætla, might already suffice.

A friend of mine asked me why I didn't use "einsetu- (hermit) constructions", because monoisotopal elements could indeed as well be designated as "hermit elements" (einsetuefni). Add to this the fact the beryllium MONOtope was into the bargain created occasionly in the cold, void extrastellar space, completely in opposite to the other elements formed together in a stellar fusion process or neutron absorption in supernova events and he "hermit-idea" becomes a very interesting avenue of thought. But for the time being I'm not inclined to loose the connection with "-sæta" in samsæta, so I stick with einsætlingsefni instead of einsetlumálmur for the time being.

The interesting thing here is that a whole element can be terminologically isolated merely by building further upon the term samsæta (isotope): einsæta (monoisotope), einsætla, einsætlingur (the smallest monoisotope, which is beryllium-9) and finally einsætlingsefni (the element beryllium itself).

The line of thought is as follows: samsæta (isotope) - einsæta (monoisotope, monotope or "hermit element" if you like) - einsætlingur ("small monotope" which most appropraitely would designate Beryllium-9, the smallest monotope on the periodic system) - einsætlingsefni (dwarf of the monotopic elements) or einsetlumálmur (the "little hermit" of the periodic system, the "little hermit metal".)

2) harðmelmlingur ("hard dwarf metal"): Lithium and beryllium are the lightest metallic elements so melmlingur actually could, apart from its use on its own to designate lithium, be used as a positioning marker for the two lightest metallic elements on the periodic system: lithium and beryllium: melmlingur on itself for lithium and harðmelmingur for beryllium. The addition of harður distinguishes beryllium, a hard metal from the very weak alkaline metal lithium.

3) njálfur (nonalphium, based upon the alternative name for He-3, trialphium, ní (nine + alfa (particle) and then shaped as much as possible after the word "málmur", Personally, I find trialphium an all but perfect piece of terminology as it could as well be serve as a designation of carbon-12, which is formed in the so-called "triple-alpha-process" (þrjálfun), where He-4 nuclei are fused to carbon-12. But since the term exists, "trialphium" could be used as a kind of "terminological scaffold", if we may call it so, to construct the term "nonalphium", the nucleus consisting of two alpha-particles and one extra nucleus, which is Be-9. A construction with -alfa is relevant for beryllium because it alludes to the fact that fusing two alpha particles doesn't work, it directly decays into two alpha-particles again, it requires an extra nucleon to get to the stable monoisotopic and primordial nuclide Be-9.

4) smál: (smá + ál): Refers to beryllium's nature of being a kind of "light version" of aluminium, with whom it constitutes the metallic part in beryl (Be₃Al₂(SiO₃)_6). Beryllium is chemically more similar to aluminium than its close neighbors in the periodic table due to having a similar charge-to-radius ratio. The word smál also rhymes on stál (steel), which alludes to its "steel-gray" color and the fact it's being almost as hard as steel (beryllium scores 5.5 on Mohs scale, and steel 6). The neologism also alliterates also with smaragður (emerald), the green beryl-variety in which the French chemist François-Nicolas Vauquelin discovered the element in 1798.

5) regði (i-shift of -ragður, the latter part of "smaragður" (emerald), the gem in which the element was discovered by the Frenchman Nicholas-Louis Vauquelin (Nikulás Lúðvík Valkalín). see http://lotukerfi.blogspot.be/2012/06/beryllium-problem-solved.html
I know it is a bold and risky construction but there are other examples like tálknamandra for the axolotl salamander. In this particular case "mandra" was cut from "salamandra" to serve as a second element. There are many examples of this kind of word-lenght reduction in Icelandic neologistic work. I did the same with smaragður (emerald), because the element was first discovered in this very variety of beryl. Of course, I went somewhat further by additionally i-shifting the left-over ragður to regði in order to obtain an i-shifted element name like ildi (from eldur), vetni (from vatn) and lyfti (from loft, once proposed for nitrogen). Regði from smaragður, a bold construction indeed, but still, why not? After all, beryllium (regði) is a part of the aluminium-berillium silicate (álregðiskíslungur) beryl Be₃Al₂(SiO₃)_{6 .} It looks completely Icelandic and there are no connotations with any other word.

6) valkalín (Vauquelium): The discoverer of berylium was the French pharmacist and chemist Nicolas-Louis Vauquelin, whose surname is of Germanic origin and transformable into Icelandic. The addition -ál refers to its being more chemically similar to aluminium than its close neighbours on the periodic table due to having a similar charge-to-radius ratio.
Porté en Normandie (76, 14), c'est un nom de personne d'origine germanique, Walkelin, rattaché par M.T. Morlet au moyen-haut-allemand walkan (= fouler). see http://jeantosti.com/noms/v2.htm
It's a masculine name on -ín, comparable to Hagalín, Espólín, Frakklín.
The funny thing about this word is that the Icelandicized form of the French name contains "alkalí" that is found in jarðalkalímálmur, while the so-called "diagonal relationship" with aluminum is expressed by the latter element -ál.
Lithium and beryllium, the first elements of Group 1 and Group 2 respectively exhibit some properties which are different from those of the other members of the respective group. In these anomalous properties they resemble the second element of the following group. Thus, lithium shows similarities to magnesium and beryllium to aluminium in many of their properties. This type of diagonal similarity is commonly referred to as diagonal relationship in the periodic table.
see http://textbook.s-anand.net/ncert/class-11/chemistry/9-the-s-block-elements

7) lotungsstál (the "steel" (hard metal) on a small period (lotungur, diminutive of lota), which is beryllium. Lithium is a weak metal, while the rest of the elements on the second period are mettaloid, non-metallic or noble gas)

2) Magnesium
Many possibilities: klémálmur (kléberg is synonymous with tálgusteinn (soap-stone), which is a major magnesium mineral, esjumálmur (esja in an old word for tálgusteinn, see Íslensk orðsifjabók and coincidentially rhymes on the latter part of the name Magnesia, the Greek city magnesium minerals were named after), leifturmálmur (after leifturljós (flash light), because magnesium has the unique property to burn with a light resembling a lightening-flash.  For this reason it was used for flash-lights in the early days of photography.  Telki, the i-shift derivation of "talk", a major magnesium mineral. mjúkhallsmálmur (mjúkhallur is an alternative name for "talcum", because it is the softest stone, only 1 on mohs scale of hardness) and last but not least tylfi (i-shift of tólf), because magnesium is the twelfth element.

3) Calcium
1) beinefni, beinmálmur, beinstoð (bone-metal, no mistake here)
2) kelki (i-shift of the word kalk (limestone))

4) Strontium
1) skoskmálmur (scotsmetal), skotakelki (calcium of the scots) (The only METALLIC element that can be linked up with Scotland, being named after the scottish village of Strontian.  If you google strontium and "Scottish element" you'll find sites that speak about strontium as "the Scottish element". Calcium's heavier brother could indeed be regarded as Scotland's representative on the periodic table, in the same way as germanium is for Germany, scandium for the whole of Scandinavia, francium for France, ruthernium for Russia, polonium for Poland, californium for California, and Niels Bohr's ultimately rejected suggestion danium for the element hafnium, which was named for Copenhagen. Judging from these examples, it is not far-fetched to assume that propositions like caledonium or scotium could have been made in the time of the element's discovery.
2) nýkelki (the "new" calcium, or the "additional bone-metal", the true earth alkaline metal found associated with calcium in the bones, which is strontium)
3) beinsilfur ("bone-silver", the osteophilic (bone-loving) element on the period of "silver", which could be yet another way to denote the alkaline earth metal.  This term is, unfortunately, not much more than a mere cross-wise positioning of the element. On the 5th period, the only element for which there are names in Old Icelandic are silfur and tin, so I used silfur as a positioning tool to terminologically isolate some metallic elements on the fifth period.  It could, occasionally, function as a hint for a student, which enables him to find the element on a periodic table lying before him on his desk.  Many chemist, though,  have a problem with "silfur" as the second element in the name, because silver is a monovalent, noble metal, while strontium is divalent, very unnoble an reactive.  In that respect the first option skoskmálmur is more neutral.

5) Barium
þungjörðungur: An extension of  þungjörð (ritmálssafn orðabókar háskólans), the translation of "heavy earth", which is an old term to designate natural barium oxide (BaO).

6) Radium
see: http://lotukerfi.blogspot.be/2012/08/polonium-mariubly-pulinamalmur-ok-that.html

Flý (flerovium)

It's official: the newly discovered element has a name: Flerovium.  It is the superheavy brother of "lead" on the 7th period and symbol is Fl and was named after the Russian scientist Georgy Flyorov.  I thought: Why not calling it FL­Ý? This word has exactly the first three first characters of the surname, it rhymes on "blý" (lead) and sounds like the verb "flýja" (flee, escape), which is a convenient connotation because the element is very unstable in comparison to lead.