Atomic Structure

Hydrogen has three isotopes with mass numbers of 1, 2, and 3 and has an average atomic mass of 1.00794 amu. This information indicates that

• equal numbers of each isotope are present

• more isotopes have an atomic mass of 2 or 3 than of 1

• more isotopes have an atomic mass of 1 than of 2 or 3

• isotopes have only an atomic mass of 1

Which electron shell in an atom of calcium in the ground state has an electron with the greatest amount of energy?

• 1

• 2

• 3

• 4

Tags

NGSS.HS-PS1-1

An orbital is a region in an atom where there is a high probability of finding

• an alpha

• an electron

• a neutron

• a positron

In all atoms of bismuth, the number of electrons must equal the

• number of protons

• number of neutrons

• sum of the number of neutrons and protons

• difference between the number of neutrons and protons

Tags

NGSS.HS-PS1-7

Which statement describes the earliest model of the atom?

• An atom is an indivisible hard sphere

• An atom has a small, dense nucleus

• Electrons are negative particles in an atom

• Electrons in an atom have wave-like properties.

Atoms are neutral because the number of

• protons equals the number of neutrons

• protons equals the number of electrons

• neutrons is greater than the number of protons

• neutrons is greater than the number of electrons

Tags

NGSS.HS-PS1-7

An ion that consists of 7 protons, 9 neutrons, and 10 electrons has a net charge of

• -2

• +2

• +3

• -3

Given a list of atomic model descriptions:

A: electron shells outside a central nucleus

B: hard, indivisible sphere

C: mostly empty space

Which list of atomic model descriptions represents the order of historical development from the earliest to most recent?

• A, B, C

• A,C, B

• B, C, A

• B, a, C

Which particle has the least mass?

• a proton

• an electron

• a helium atom

• a hydrogen atom

Which phrase describes the charge and mass of a neutron?

• a charge of +1 and no mass

• a charge of +1 and an approximate mass of 1 u

• no charge and no mass

• no charge and an approximate mass of 1 u