Definitions

Question 0

Matter

Answer 0

Substance that has mass and takes up space.

Question 1

Chemistry

Answer 1

The science of the materials that make up the universe-what they are made of, how they interact, and how they change.

Question 2

Solid

Answer 2

A form of matter that has a definite shape and volume.

Question 3

Liquid

Answer 3

A form of matter that does not have a definite shape but has a definite volume. A liquid conforms to the shape of its container.

Question 4

Gas

Answer 4

A form of matter that has no definite shape, weight, or size. The volume (size) of a gas is related to its temperature and the pressure being placed on it by its environment.

Question 5

Plasma

Answer 5

A hot gas whose matter is broken into charged particles. Plasma exists in areas of extreme heat, like the center of stars.

Question 6

Element

Answer 6

A specific form of matter composed of only one type of atom. Elements cannot be divided into different types of matter. Elements are classified by the number of protons in an atom of that element.

Question 7

Compound

Answer 7

Two or more elements combined chemically. The compound has different chemical properties than those of its individual elements, and it can only be separated by chemical means.

Question 8

Mixture

Answer 8

Two or more elements that are combined physically rather than chemically. The individual elements retain their own chemical properties and can be separated by physical means.

Question 9

Proton

Answer 9

One of the principal particles of an atom. The proton has a positive electrical charge, and is found in the nucleus of an atom. A proton weighs one atomic mass unit.

Question 10

Neutron

Answer 10

One of the principal particles in an atom. The neutron has no electric charge, and is found in the nucleus of an atom. The mass of a neutron is about one atomic mass unit.

Question 11

Electron

Answer 11

The smallest significant particle in an atom. Electrons have a negative charge and orbit around the nucleus.

Question 12

Quark

Answer 12

A sub atomic particle that makes up protons and neutrons. Quarks are divided into “up” quarks, which have a charge of positive 2/3, and “down” quarks, which have a charge of negative 1/3. Protons are made up of two up quarks and one down quark, giving them a total charge of positive one. Neutrons are made of two down quarks and one up quark, giving them a total charge of zero.

Question 13

Lepton

Answer 13

Family of particles (as electrons, muons, and neutrinos) that experience no strong forces.

Question 14

Nucleus

Answer 14

The central core of an atom. The nucleus is made of protons and neutrons. The electrons circle around the nucleus.

Question 15

Ion

Answer 15

A variation of an atom or atoms based on the loss or gain of an electron. This changes the charge of the atom.

Question 16

Cation

Answer 16

An atom that has lost an electron. Cations have more protons than electrons, giving them a positive charge.

Question 17

Anion

Answer 17

An atom that has gained an electron. Anions have more electrons than protons, giving them a negative charge.

Question 18

Atomic mass

Answer 18

The total average number of protons and neutrons in an atom. A measurement of the mass of an atom can be estimated by calculating the total number of protons and neutrons in the atom’s nucleus. Atomic mass is measured in atomic units.

Question 19

Atomic mass units (amu)

Answer 19

A unit of measurement for the mass (size or largeness) of an atom. One atomic mass unit is roughly equal to the mass of one proton, 1.66*10^-27 kg.

Question 20

Periodic Table of Elements

Answer 20

A system of organization for the elements. Elements are positioned based on their atomic number and type. The Periodic Table lists information about each element, including atomic number, atomic mass, and symbol.

Question 21

Atomic number

Answer 21

The number of protons contained in an atom. Each element has its own invariable atomic number. The atomic number is often used to identify elements.

Question 22

Period

Answer 22

The name for a row in The Periodic Table of Elements. Periods are determined by the highest energy level where electrons can be found in an atom. Elements found in the lower periods of the Periodic Table have much higher energy than those found in the upper periods.

Question 23

Group

Answer 23

The name for a column in the Periodic Table of elements. Groups are generally divided based on the number valence electrons in an atom of the element. In the United States, groups are numbered with Roman numerals and capital letters, e.g., I-VIIIA and I-VIIIB

Question 24

Metal

Answer 24

In the Periodic Table of Elements, the most abundant of the three broad categories into which elements are classified based on their properties. Metals are good conductors of electricity and have a metallic sheen. They can be molded or stretched without breaking.

Question 25

Nonmetal

Answer 25

In the Periodic Table of Elements, one of the three broad categories into which elements are classified based on their properties. Nonmetals, in a solid form, do not gleam, are poor conductors, and tend to be fragile.

Question 26

Metalloid

Answer 26

In the Periodic Table of Elements, one of the three broad categories into which elements are classified based on their properties. Metalloids are also called semimetals, or semiconductors. Metalloids sometimes have the metallic gleam of metals, but are more fragile. They can conduct heat and electricity but not as well as metals.

Question 27

Isotope

Answer 27

A variation of an element based on the number of neutrons in its nucleus.

Question 28

Electron configuration

Answer 28

The organization of electrons around the nucleus of an atom. The electron configuration of an element is determined by the number of electrons it possesses and their position in the energy levels around the atom

Question 29

Orbital

Answer 29

Another name for an energy level; a field that defines the pattern and position in which electrons move about the nucleus of an atom. The outermost orbitals give shape to the atom.

Question 30

Energy level

Answer 30

A region surrounding the nucleus of an atom. Electrons move around the nucleus in energy levels. The location and behavior of electrons can be predicted based on these energy levels. Energy levels closer to the nucleus have lower energy than those farther away.

Question 31

Electron cloud

Answer 31

A region around the nucleus in which electrons are predicted to be found at any given point. Electron cloud are sometimes represented as orbitals or energy levels. Electron clouds are used to approximate the location and behavior of electrons.

Question 32

Valence electron

Answer 32

Valence electrons an electron in the outermost (usually incomplete) orbital of an atom. Every element has a unique number of valence electrons. Valence electrons determine how an element combines with other elements.

Question 33

Molecule

Answer 33

A group of atoms linked by a chemical bond. A molecule is the smallest independent unit of a compound.

Question 34

Covalent bond

Answer 34

A chemical bond between two (generally similar) elements. Covalent bonding occurs when one atom shares electron(s) with another atom, creating a bond between the two atoms as they both attract the shared electron(s).

Question 35

Ionic bond

Answer 35

A chemical bond between two (generally dissimilar) elements. Ionic bonding occurs when one atom gives electron(s) to the other atom, making both atoms into ions that bond with each other.

Question 36

Homonuclear diatomic

Answer 36

A molecule composed of two identical or the same type of atoms. H2 is an example.

Question 37

Molecular mass

Answer 37

The combined masses of each atom in a molecule.

Question 38

Mole

Answer 38

A group of atoms or molecules that total 6.022*10^23. The mole is a convenient conversion unit for chemistry calculations.

Question 39

Lewis structures

Answer 39

Electron dot diagrams developed by Gilbert Newton Lewis in the early 1900s to illustrate valence electrons in elements. The structures are used to show the changes in electron orbital structures caused by chemical bonding.