Zinc is a metal, and you need it for your immune system, and possibly also for your sense of smell.
Well, not quite the same. Lithium, Sodium, Potassium, Cesium 9and Francium) are Alkai metals. Calcium and Magnesium are Alkaline Earths. The two groups have different properties. I know because
1.) I did a deep report on the alkali metals back in high school.
b.) years later I ended up working with the alkali earths, both in pure form and in alkali halide crystals. They’re pretty fascinating, as long as you handle them carefully.
Did you know the alkali metals are transparent in the ultraviolet? With a UV light source and detector, you can see through them (!)
So why were not alkali dresses extremely popular (at least with guys) at the end of the 1960s?
Gotta be a good use for that.
Hey, can I hijack this discussion about diet and metals for a moment? There is a drink called Tava and on the side of the bottle, it proudly proclaims to be a good source of chromium. How much chromium do I in fact need? Is this a worthwhile reason to drink Tava or do I risk a surfeit of chromium?
Leading to one of my favorite geeky songs, NaCl by the McGarrigle Sisters:
Then unsuspecting chlorine
Felt a magnetic pull
She looked down and her outside shell was full
Sodium cried, “What a gas! Be my bride
And I’ll change your name from chlorine to chloride.”
Yeah – I figure if you put a layer of alkali metal between plates of some UV-transmitting material (Like LiF – Lithium Fluoride, oddly enough) you can make UV bandpass filters. Choose your metal and the plates correctly and you can vary your peak transmission and width.
Just keep 'em away from water…
Shit, I knew not paying enough attention in chemistry would catch up with me.
Hydrogen is not a metal. The fact that there is a form of hydrogen with metallic properties does not make hydrogen a metal. Hydrogen is unique among the elements.
This is absurd. Metallic hydrogen is a metal. Hydrogen is still unique, and hydrogen in other forms is not a metal. Neither are calcium ions dissolved in water. So what?
Calcium when bonded to carbon forms an extremely nucleophilic carbon. This is the same with all low MW metals and pretty universal to all metals. Hydrogen forms a very stable bond with carbon. The bonding isn’t remotely metallic.
Elemental carbon can be metallic in the right configuration even at room temperature, but nobody is calling that a metal.
Only when it’s in a configuration that requires construction. You don’t just happen to fall into metallic nanotubes or metallic planar carbon. And the technology’s still pretty new – they may end up calling it “metallic” yet.
OTOH, if you put hydrogen at the right temperature and pressure, it’s got those metallic properties – no special construction required.
Brainiac’s take on alkali metals (not Calcium).
Because a drop of rain would have caused the wearer to burst out in flames. Human Torch, eat your heart out.
Several years back, a ship loaded with Sodium metal (“drowned” in organic solvent and contained in hermetic barrels) sunk before the Spanish coast. When the water pressure managed to breach a barrel, it would zzZZZZZZZZOOM out and go skipping over the water. We used to do something similar in the Orgo I lab with tiny pieces of sodium and a puddle on the floor, but let me tell you, those images of the ship on TV were real spectacular.
Question - is liquid hydrogen considered a metal?
Ironically, according to the Wiki, one of the few places that metallic hydrogen can be found is in the center of large, faraway planets. It’s ironic because astrophysically speaking hydrogen isn’t a metal. So it’s only found in outer space as a metal, but in outer space it isn’t considered a metal 
Youtube video of barrels of sodium exploding.
It doesn’t matter. Calling hydrogen a metal is stretching the definition of metal beyond what any chemist would call a metal. It only has some metallic properties at extreme pressures, it has no other metallic properties. Metals and hydrogen do not even remotely bond the same way.
No. Only hydrogen at extremely high pressures has metallic properties.
Well, there goes my dream of getting rich selling calcium based sunscreen. 
Well calcium oxide is probably quite a good sunscreen, but the whole reacts with water to produce caustic calcium hydroxide would probably ruin your plan.