chemistry unit 3

What is the charge of the nucleus of an oxygen atom? A) 0 B) -2 C) +8 D) +16

+8

The atomic mass of an atom is measured in atomic mass units. This unit is based on A) 1H B) 14N C) 16O D) 12C Response

12c

What is the mass number of an atom that has six protons, six electrons, and eight neutrons? A) 6 B) 12 C) 14 D) 20

14

What is the mass number of 19 9F? A) 9 B) 10 C) 19 D) 28

19

n atom of fluorine has a mass of 19 atomic mass units. The total number of protons and neutrons in its nucleus is A) 9 B) 10 C) 19 D) 28

19

An ion that consists of 7 protons, 9 neutrons, and 10 electrons has a net charge of -2 +2 +3 -3

-3

What is the mass number of an atom that contains 19 protons, 19 electrons, and 20 neutrons? A) 19 B) 20 C) 39 D) 58

39

What is the atomic number of an element that has six protons and eight neutrons? A) 6 B) 2 C) 8 D) 14

6

Which sequence represents a correct order of historical developments leading to the modern model of the atom? A) the atom is a hard sphere → most of the atom is empty space → electrons exist in orbitals outside the nucleus B) the atom is a hard sphere → electrons exist in orbitals outside the nucleus → most of the atom is empty space C) most of the atom is empty space → electrons exist in orbitals outside the nucleus → the atom is a hard sphere D) most of the atom is empty space → the atom is a hard sphere → electrons exist in orbitals outside the nucleus

A) the atom is a hard sphere → most of the atom is empty space → electrons exist in orbitals outside the nucleus

The stability of an isotope is related to its ratio of A) neutrons to positrons B) neutrons to protons C) electrons to positrons D) electrons to protons

B) neutrons to protons

If two atoms are isotopes of the same element, the atoms must have A) the same number of protons and the same number of neutrons B) the same number of protons and a different number of neutrons C) a different number of protons and the same number of neutrons D) a different number of protons and a different number of neutrons

B) the same number of protons and a different number of neutrons

he atoms in a sample of an element must contain nuclei with the same number of A) electrons B) protons C) neutrons D) nucleons

B) protons

The number of neutrons in the nucleus of an atom can be determined by A) adding the atomic number to the mass number B) subtracting the atomic number from the mass number C) adding the mass number to the atomic mass D) subtracting the mass number from the atomic number

B) subtracting the atomic number from the mass number

An atom that contains 8 protons, 8 electrons, and 9 neutrons has A) an atomic number of 9 B) an atomic number of 16 C) a mass number of 17 D) a mass number of 25

a mass number of 17

Which of the following particles has the smallest mass. neutron electron proton hydrogen atom

electron

Which subatomic particles are located in the nucleus of a carbon atom? A) protons, only B) neutrons, only C) protons and neutrons D) protons and electron

protons and neutrons

The atomic mass of an element is the weighted average of the atomic masses of A) the least abundant isotopes of the element B) the naturally occurring isotopes of the element C) the artificially produced isotopes of the element D) the natural and artificial isotopes of the element

the naturally occurring isotopes of the element

An atom of helium-4 differs from an atom of lithium-7 in that the atom of helium-4 has A) one more proton B) one more neutron C) two less protons D) two less neutrons

two less neutrons