chapter 4

Question 1

atom

Answer 1

the smallest unit of an element that maintains the properties of that element

Question 2

electron

Answer 2

a subatomic particle that has a negative charge

Question 3

nucleus

Answer 3

in physical science an atom’s central region which is made up of protons and neutrons

Question 4

electron clouds

Answer 4

a region around the nucleus of an atom where electrons are likely to be found

Question 5

proton

Answer 5

a subatomic particle that has a positive charge and that is found in the nucleus of an atom

Question 6

atomic mass unit

Answer 6

a unit of mass that describes the mass of an atom or molecule

Question 7

neutron

Answer 7

a subatomic particle that has no charge and the nucleus of an atom

Question 8

atomic number

Answer 8

the number of protons in the nucleus of an atom the atomic number is the same for all atoms of an element

Question 9

isotope

Answer 9

an atom that has the same number of protons or the same atomic number as other atoms of the same element do but that has a different number of neutrons and thus a different atomic mass

Question 10

mass number

Answer 10

the sum of the numbers of protons and neutrons in the nucleus of an atom

Question 11

atomic mass

Answer 11

the mass of an atom expressed in atomic mass units

Question 12

Dalton

Answer 12

All substances are made of atoms, atoms of the same element are exactly alike, atoms join together with other atoms too make new substances.

Question 13

Thomson

Answer 13

He showed that there was a mistake in Dalton’s theory .

Question 14

Rutherford

Answer 14

Some particles turned to one side and others went straight in his theory

Question 15

Bohr

Answer 15

This led him to a purpose that electrons move around the nucles