Bio I CP Unit 2 Test Review - Chemistry of Life

What determines the atomic number of an atom?

• the number of electrons in the outermost energy level
• the number of protons in the nucleus
• arrangement of neutrons in the nucleus
• total number of energy shells

Why is a helium atom (atomic number 2) more stable than a hydrogen atom (atomic number 1)?

• eight electrons completely fill its outermost electron shell
• two electrons completely fill its outermost electron shell
• the outermost electron shell is half empty

Which of the following factors is the most important when deciding if an atom will bond?

• an atom is the smallest particle of an element
• a molecule is the smallest unit of a compound
• how many electrons are in the valence shell

For an atom to achieve maximum stability and become chemically unreactive what must occur?

• sharing of electron pairs is necessary
• it must be inert
• its outermost energy shell must be filled with electrons
• ionization is required

An atom's nucleus is composed of

• protons and electrons
• protons
• neutrons
• protons and neutrons

Sodium (Na), atomic number 11, has a tendency to lose an electron in the presence of chlorine. After losing the electron, Na will have ___ PROTONS in its nucleus.

• 10
• 22
• 11
• 12

How does one explain the formation of ions?

• gain or loss of electrons
• sharing of protons
• gain or loss of protons
• sharing of electrons

Phosphorous has an atomic number of 15, so what will the distribution of electrons be

• first level, second level and third level will have 5 electrons each
• the first level will have 2, the second will have 13
• the first level will have 2, the second will have 8, and the third will have 5
• arrangement cannot be determined from atomic number

Polar covalent bonds form when

• an acid and base are combined
• more than one pair of electrons is shared
• electrons are shared unequally between atoms
• ions are formed

The hydrogen bond between two water molecules arises because water is

• a liquid
• nonpolar
• hydrophobic
• polar