Unit 1-Atomic Theory

What is the total number of valence electrons in an atom with the electron configuration 2-8-5?

• 2

• 5

• 8

• 15

Tags

NGSS.HS-PS1-1

A Ca2+ ion differs from a Ca0 atom in that the Ca2+ ion has

• more electrons

• more protons

• fewer protons

• fewer electrons

Tags

NGSS.HS-PS1-1

Which particles are referred to as nucleons (subatomic particles located in the nucleus)?

• protons and neutrons

• protons and electrons

• neutrons, only

• neutrons and electrons

Tags

NGSS.HS-PS1-8

What is the mass number of an atom that contains 19 protons, 19 electrons, and 20 neutrons?

• 39

• 19

• 58

• 20

What term refers to the region of an atom where an electron is most likely to be found?

• quantum

• spectrum

• orbital

• orbit

The nucleus of an atom consists of 8 protons and 6 neutrons. The total number of electrons present in a neutral atom of this element is

• 6

• 8

• 2

• 14

Tags

NGSS.HS-PS1-1

What is the maximum number of electrons that can occupy the third principle energy level?

• 18

• 8

• 10

• 3

Atoms of 16O, 17O, and 18O have the same number of

• protons, but a different number of electrons

• electrons, but a different number of protons

• protons, but a different number of neutrons

• neutrons, but a different number of protons

All atoms of an element have the same

• number of neutrons

• atomic mass

• atomic number

• mass number

The atomic number is always equal to the total number of

• neutrons in the nucleus

• protons in the nucleus

• neutrons plus protons in the atom

• protons plus electrons in the atom