Chapter 2 Vocabulary

Question 1

Law of conservation of mass

Answer 1

In a chemical reaction, matter is neither created nor destroyed.

Question 2

Law of definitie proportions

Answer 2

All samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constitutent elemtents.

Ex: Mass ratio = 16.0 g O / 2.0 g H = 8.0 or 8:1

Question 3

Law of multiple proportions

Answer 3

When two elements (call them A and B) form two different compounds, the masses of element B that combine with 1 g of element A can be expressed as a ratio of small whole numbers.

Question 4

Atomic theory

Answer 4

John Dalton proposed the atomic theory, whcih included the followign concepts:

1) Each element is composed of tiny, indestructible particales called atoms.
2) All atoms of a given element have the same mass and other properties that distinguish them from the atoms of other elements.
3) Atoms combine in simple, whole-number ratios to form compounds
4) Atoms of one element cannot change into atoms of another element. In a chemical reaction, atoms only change the way that they are bounded together with other atoms.

Question 5

Electron

Answer 5

A negatively charges, low mass particle found outside the nucleus of all atoms that occupies most of the atom’s volume but contributes almost none of its mass.

Question 6

Proton

Answer 6

A positively charged subatomic particle found in the nucleus of an atom.

Question 7

Neutron

Answer 7

An electrically neutral subatomic particle found in the nucleus of an ato, with a mass almost equal to that of a proton.

Question 8

Atomic number (Z)

Answer 8

The number of protons in an atom; the atomic number defines the element.

Question 9

Chemical Symbol

Answer 9

A one- or two-letter abbreviation for an element that is listed directly below its atomic number on the periodic table.

Question 10

Isotopes

Answer 10

Atoms of the same element with the same number of protons but different numbers of neutrons and consequently different masses.

Question 11

Natural abundance

Answer 11

The relative percentage of a particular isotope in a naturally occurring sample with respect to other isotopes of the same element.

Question 12

Mass number (A)

Answer 12

The sume of the number of protons and neutrons in an atom.

Question 13

Ion

Answer 13

An atom or molecule with a net charge caused by the loss or gain of electrons.

Question 14

Cation

Answer 14

A positively charge ion.

Question 15

Anion

Answer 15

A negatively charged ion.

Question 16

Electrical Charge

Answer 16

A fundamental property of certain particles that causes them to experience a force in the presence of electrical fields.