Multiple choice chemistry problems?

Question

I need help with these multiple choice questions:

IDENTIFY THE PAIR OF ATOMS THAT ARE EXPECTED TO HAVE CLOSE SIMILARITIES IN THE ELECTRON CONFIGURATION, ESPECIALLU THE OUTER SHELL (ORBIT)?

a) boron and aluminum

b) silicon and phosphorous

c) aluminum and silicon

d) helium and neon

ON THE BASIS OF THE PERIODIC TABLE, WHAT IS THE SIMILARITY BETWEEN THE ELEMENTS IN A PERIOD (ROW)?

a) the elements in a period all have the same number of electrons

b) the elements in a period all have the same number of neutrons

c) the elements in a period all have the same number of orbits or shells

d) there is no similarity, the elements fall into the periods on the basis of the way in which the groups are filled.

Answer 1

1)

Elements in groups (columns going down the table) all have the same number of electrons in their outer electron shell with one exception and that is group 8. Helium (He) only has 2 electrons in it's outer shell and all the other elements in group 8 have 8 electrons in the outer shell.

Correct answer is a) Boron and Aluminium. Both are in group 3 and thus have 3 electrons in their outer shell.

For b) and d) the two elements in both are in different groups and so do not have the same number of electrons in outer shell.

d) I have explained above. He has a full outer electron shell, but for He, a full outer electron shell means 2 electrons. All other group 8 atoms have 8 electrons in outer shell.

2) a) No, they all have different atomic numbers, and thus different numbers of protons in the neucleus. Since for a neutral atom number of electron = number of protons then this is not correct.

b) No, Number of neutrons = atomic mass - atomic number. This varied along a period also

c) No, In the 4th period (the one starting with K) K and Ca have electrons in the 4s orbital but then the transition metals (starting with Sc) start filling in the 3 d orbital, so clearly this is not true. See the below link for a green diagram that shows what order orbitals fill in.

http://www.webchem.net/notes/atomic_stru...

d) answer must be d)