A collection of atoms of one type that cannot be broken down into simpler substances by ordinary chemical or physical means

• element

• subatomic particle

• electron

• matter

A negatively charged subatomic particle that orbits the nucleus of an atom

• proton

• neutron

• electron

• matter

One or two letters that represent the name of an element

• element name

• atomic symbol

• atomic number

• atomic mass

A unique number for each element that equals the number of protons in an atom of that element

• element name

• element symbol

• atomic number

• atomic mass

The mass of an atom, calculated by adding the number of protons and neutrons in the nucleus of the atom

• element name

• element symbol

• atomic number

• atomic mass

A grouping of elements based on similar properties arranged vertically in the periodic table; each element in each column contains the same number of valence electrons.

• group

• period

• row

• isotope

Answer explanation

Valence electrons are found on the outermost energy shell.

A horizontal grouping on the Periodic Table of Elements. Each element in each row has the same number of energy shells.

• family

• period

• row

• isotope

Answer explanation

The Bohr Model shows these energy levels.

How many protons does potassium have?

• 39.0983

• 19

• 20

• 10

What element is in period 6 and group 14?

• Ar (Argon)

• O (Oxygen)

• Pb (Lead)

• Fe (Iron)

Answer explanation

Lead has 6 electron shells because it's in period 6 and 4 valence electrons because it's in group 14.

Potassium is in group 1 and period 4. How many valence electrons does it have?

• 1

• 4

• 5

• 3

Answer explanation

Elements in the same group have the same number of valence electrons.