Science Vocab

Question 1

The smallest unit of an element, consisting of at least one proton and (for all elements except hydrogen) one or more neutrons in a dense central nucleus, surrounded by one or more shells of electrons.

Answer 1

Atom

Question 2

The mass of an atom, usually expressed in atomic mass units. Total number of particles in the nucleus of an atom.

Answer 2

Atomic mass

Question 3

The number of protons in the nucleus of an atom

Answer 3

Atomic Number

Question 4

A substance consisting of atoms or ions of two or more different elements in definite proportions joined by chemical bonds into a molecule.

Answer 4

Compound

Question 5

A property or characteristic of a substance that is observed during a reaction in which the chemical composition or identity of the substance is changed.

Answer 5

Chemical Property

Question 6

A measure of the mass of a substance per unit volume.

Answer 6

Density

Question 7

An elementary particle with a negative charge and a very small mass. Electrons are normally found in orbits around the nucleus of an atom.

Answer 7

Electron

Question 8

The orbital path that is followed by electrons around the nucleus of an atom. It is also known as an energy level.

Answer 8

Electron Shell

Question 9

A substance that cannot be broken down into simpler substances by chemical means. An element is composed of atoms that have the same atomic number.

Answer 9

Element

Question 10

One of four main states of matter, composed of molecules in constant random motion. Unlike a solid, a gas has no fixed shape and will take on the shape of the space available.

Answer 10

Gas

Question 11

Liquid

Answer 11

One of four main states of matter, composed of molecules that can move about in a substance but are bound loosely together by intramolecular forces. Unlike a solid, a liquid has no fixed shape, but instead has a characteristic readiness to flow and therefore takes on the shape of any container.

Question 12

A substance that occupies space and has mass.

Answer 12

Matter

Question 13

A composition of two or more substances that are not chemically combined with each other and are capable of being separated.

Answer 13

Mixture

Question 14

A group of two or more atoms linked together by sharing electrons in a chemical bond. Molecules are the fundamental components of chemical compounds and are the smallest part of a compound.

Answer 14

Molecule

Question 15

An elementary particle without an electrical charge; one of the building blocks of the nucleus of the atom. A neutron has about the same mass as a proton.

Answer 15

Neutron

Question 16

The positively charged central region of an atom, composed of one or more protons and (for all atoms except hydrogen) one or more neutrons, containing most of the mass of the atom.

Answer 16

Nucleus

Question 17

A characteristic of matter that can be observed and measured without changing the chemical identity of the substance.

Answer 17

Physical Property

Question 18

An elementary particle with a positive charge, found in the nucleus of an atom.

Answer 18

Proton

Question 19

One of four main states of matter, in which the molecules vibrate about fixed positions and cannot migrate to other positions in the substance. Unlike a gas or liquid, a solid has a fixed shape, and unlike a gas, a solid has a fixed volume.

Answer 19

Solid

Question 20

A type of matter with definite chemical composition

Answer 20

Substance