The Periodic Table

The order of elements in the periodic table is based on

• the number of protons in the nucleus.

• the electric charge of the nucleus.

• the number of neutrons in the nucleus.

• atomic mass.

Atoms of elements that are in the same group have the same number of

• protons.

• neutrons.

• valence electrons.

• protons and neutrons.

Which of the following elements is an alkali metal?

• calcium

• magnesium

• mercury

• sodium

In Mendeleev's periodic table, elements in each column had similar

• atomic masses.

• properties.

• atomic numbers.

• symbols.

How was Mendeleev's periodic table arranged?

• by increasing atomic mass

• by decreasing atomic mass

• by increasing atomic number

• by decreasing atomic number

Mendeleev left gaps in his periodic table because

• the table was too small.

• protons belonged there.

• the table was too full.

• no known elements fit there.

Each column of the periodic table is

• an element.

• a group.

• an isotope.

• a period.

The three main groups of elements are metals, nonmetals, and

• inert gases.

• alkali metals.

• radioactive isotopes.

• semiconductors/metalloids.

Most elements are

• metals.

• nonmetals.

• metalloids.

• semiconductors.

The order of elements in the modern periodic table is based on an element's

• atomic number.

• name.

• chemical symbol.

• atomic mass.