3. What is the best explanation for the decrease in first ionization energy moving from Be to B?
(A) Moving from Be to B, more electrons are added to the
atoms, thus increasing the electron-electron repulsions.
(B) Moving from Be to B, more protons in the nucleus
attract the valence electrons, making it harder to remove
the electrons.
(C) The electrons in Be are being removed from a full sub-
shell, which is more stable than the half-filled subshell
in B.
(D) The electrons in Be are located in the 2s subshell. These
electrons penetrate closer to the nucleus than the 2p
electrons in B.

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms