Question

1. an atom with electron arrangement 2-8-7 will most likely: *

become bigger when it gains electron
become bigger when it loses electron
become smaller when it gains electron
remain the same size when it gains electron

1. in a co bond, electrons in the bond are most likely attracted to: *

carbon atom, because it has lower electronegativity.
oxygen atom, because it has lower electronegativity.
carbon atom, because it has higher electronegativity.
oxygen atom, because it has higher electronegativity.

Explanation:

Question 13

An atom with electron arrangement 2 - 8 - 7 has 17 electrons, so it's a chlorine atom (or a halogen - like atom). When an atom gains an electron, it becomes an anion. The addition of an electron increases electron - electron repulsions in the outermost shell, and also, the effective nuclear charge per electron decreases slightly. This causes the electron cloud to expand, so the atom (now an anion) becomes bigger. When an atom loses an electron, it becomes a cation, and the remaining electrons are pulled more tightly by the nucleus, so the size decreases. So an atom with electron arrangement 2 - 8 - 7 (needing 1 electron to complete the octet) will become bigger when it gains an electron.

Electronegativity is the ability of an atom to attract electrons in a chemical bond. Oxygen has a higher electronegativity than carbon. In a CO bond, the more electronegative atom will attract the bonding electrons more strongly. Since oxygen is more electronegative than carbon, the electrons in the CO bond are most likely attracted to the oxygen atom.

Answer:

A. Become bigger when it gains electron

Question 14