Unit 3: Atomic Structure Practice test

Who invented nitrous oxide and carbonate water, leading to the invention of soda?

Joseph Priestly.

Who discovered the role of oxygen in combustion and formulated the Conservation of Mass?

Antoine Lavoisier.

What are atoms or groups of atoms with a positive or negative charge called?

Ions.

The mass of a single atom is measured in what unit?

Atomic Mass.

What type of ions are formed when electrons are lost?

Cations.

Opposite charges ____________ each other, while like charges ____________ each other.

Attract; repel.

An atom is ______________ when the number of protons equals the number of electrons.

Neutral.

What are formed when electrons are gained?

Anions.

Who measured the exact charge and mass of an electron?

Robert Millikan.

Who discovered the electron?

J.J. Thompson.

The atomic mass is the average of the element's what?

Isotopes.

Which group of elements tends to gain electrons?

Nonmetals.

Who gave the atom its name?

Democritus.

Who stated that all matter is composed of indivisible particles called atoms?

John Dalton.

Who was the first person to consider the idea of atoms?

Democritus.

What do lost electrons create?

Cations.

Who discovered the neutron?

Sir James Chadwick.

Who used the Gold Foil experiment to discover the nucleus?

Ernest Rutherford.

Who discovered the proton?

Eugen Goldstein.

Electrons are arranged in _____________ around the nucleus.

energy levels

Who believed everything was composed of four elements: earth, air, fire, and water?

Aristotle.

What are the four major points of Dalton’s atomic theory?

1. All elements are composed of indivisible particles called atoms. 2) Atoms of the same element are identical. 3) Atoms of different elements mix or combine in whole number ratios. 4) Chemical reactions occur when atoms separate, join, or rearrange.

An element has 3 common isotopes. The first isotope has a mass of 19.992 amu and occurs 90.48% of the time. The second isotope has a mass of 20.994 amu and occurs .27 % of the time. The third isotope has a mass of 21.991 amu and occurs 9.25 % of the time. Calculate the atomic mass of this element.

20.18 amu

An element has an average atomic mass of 39.948 amu. It has 2 common isotopes. The first isotope has a mass of 35.968 and a relative abundance of 33.65%. a) What is the % abundance of the second isotope? b) What is the mass of the second isotope?

66.35% is the abundance of the second isotope, and 41.97amu is the mass.