Chapter 4 Test (True/False, Multiple Choice, Fill in the Blank)

An unknown element has 19 protons, 19 electrons, and 3 isotopes with 20, 21, and 22 neutrons. What is the element's atomic number? _______

19

_______ concluded that atoms are mostly empty space. a) Rutherford b) Thomson c) Chadwick

A

The numbers of protons = the __________ of the element.

Atomic number

Atoms with the same number of protons but different numbers of neutrons are called _______. a) Quarks b) Isotopes c) Isopods

B

_______ identified the first subatomic particle -- the electron. a) Rutherford b) Thomson c) Millikan

B

Th atomic number is equal to the number of _______. a) Neutrons b) Protons c) Electrons

B and C

______ was the first person to propose the existence of atoms. a) Aristotle b) Copernicus c) Democritus

C

_______ discovered that atoms of each element contain a unique positive charge in their nuclei. a) Mendeleev b) Aristotle c) Moseley

C

________ are held within the atom by their attraction to the positively charged nucleus.

Electron

The smallest particle of an element that retains the properties of the element is called a(n) *electron*. (T/F)

False; atom

Nuclear reactions *cannot* change one element into another element. (T/F)

False; can

All atoms are *positive*. (T/F)

False; neutral

Isotopes all have *different* chemical behavior. (T/F)

False; same

The two subatomic particles found in the nucleus are the _______ & ________.

Neutron Proton

Scientists have determined that protons and neutrons are composed of subatomic particles called _________.

Quarks

The atomic mass of an element is an average of the *isotopes*. (T/F)

True

Elements with the same number of protons and differing numbers of neutrons are known as _________.

isotopes

Atoms that contain too many or too few neutrons are _________.

unstable