Science Notes 12/3/24

Matter

Anything that has mass and takes up space.

Substance

A single kind of matter that is pure and has a specific set of properties.

Physical property

A characteristic of a pure substance that can be observed without changing it into another substance.

Chemical property

A characteristic of a substance that describes its ability to be changed into another substance.

Atom

The basic particle from which all substances are made; the smallest particle of an element that has the properties of that element.

Element

A pure substance that cannot be broken down into other substances by chemical or physical means.

Molecule

A neutral group of two or more atoms held together by covalent bonds.

Compound

A substance made by two or more elements chemically combined in a specific ratio or proportion.

Mixture

Two or more substances that are together in the same place but whose atoms are not chemically bonded.

Mass

A measure of the amount of matter in an object.

Volume

The amount of space that matter occupies.

Weight

A measure of the force of gravity acting on an object.

Density

The measurement of how much mass of a substance is contained in a given volume.

Physical change

A change that alters the form or appearance of a material but does not make the material into another substance.

Chemical change

A change in which one or more substances combine or break apart to form new substances.

Homogeneous mixture

A mixture that cannot be easily separated into its parts (e.g., milk, soda).

Heterogeneous mixture

A mixture that can be separated (e.g., trail mix, fruit salad).

Pressure

The force pushing on a surface divided by the area of that surface.

Charles’s Law

A principle that describes the relationship between the temperature and volume of a gas at constant pressure.

Boyle’s Law

A principle that describes the relationship between the pressure and volume of a gas at constant temperature.

Electron

A tiny, negatively charged particle that moves around the outside of the nucleus of an atom.

Nucleus

The central core of an atom that contains protons and neutrons.

Proton

A small, positively charged particle that is found in the nucleus of an atom.

Neutron

A small particle in the nucleus of an atom with no electrical charge.

Atomic Number

The number of protons in the nucleus of an atom.

Isotope

An atom with the same number of protons and a different number of neutrons from other atoms of the same element.

Mass number

The sum of the protons and neutrons in the nucleus of an atom.

Cation

A positively charged ion formed when an atom loses electrons.

Anion

A negatively charged ion formed when an atom gains electrons.

Ionic bond

The force of attraction between the opposite charges of the ions in an ionic compound.

Covalent bond

A chemical bond formed through the sharing of electrons by atoms.