In Ernest Rutherford's gold foil experiment, most positively charged particles passed through the foil, but a few particles were deflected strongly. This result caused Rutherford to infer

• that electrons move in orbits around the nucleus of an atom.
• that atom's positive charge must be clustered in a tiny region in its center.
• that electrons have almost no mass.
• that an atom consists of the negative charges scattered in a ball of positive charge.

Mendeleev created the first periodic table by arranging elements in order of

• decreasing atomic mass.
• increasing atomic mass.
• increasing atomic number.
• increasing melting point and densities.

The atomic number of an element is based on the

• mass of its nucleus.
• the number of protons in its nucleus.
• number of neutrons in its nucleus.
• number of electrons around its core.

From an element's location in the periodic table, you can predict

• its properties
• its chemical name.
• its chemical symbol.
• when it was discovered.

In general, which of the following statements about metals is true?

• Metals need to be stored in sealed containers for safety.
• Metals are malleable, ductile, and can carry an electric current.
• Metals are highly reactive substances.
• Metals do not react with oxygen.

The elements that do not ordinarily form compounds are

• elements in the carbon family.
• metals.
• halogens.
• noble gases.

The modern periodic table is organized according to

• atomic mass.
• atomic weight.
• atomic number.
• valence electrons.

The horizontal rows in the periodic table are known as

• groups.
• periods.
• families.
• cousins.

Nonmetals can be found on this side of the periodic table.

• top
• bottom
• right
• left

Atoms with the same number of protons and different numbers of neutrons are called

• alloys.
• isotopes.
• positive ions.
• negative ions.