Unit 1: Introduction to Chemistry

Matter

Anything occupying space and having mass

Element

A substance that can't be broken down to another substance and is made up of one type of atom.

Atom

the basic unit of a chemical element.

Compound

Two or more elements in a fixed ratio, bonded together.

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom.

Electron

A subatomic particle that has a negative charge, almost no mass, and is found outside the nucleus in shells/orbits.

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom.

Atomic Number

The number of protons in the nucleus of an atom. Also, the number of electrons in a neutral atom.

Chemical Symbol

A one or two letter representation of an element found on the periodic table.

Atomic Mass

The average mass of all the isotopes of an element.

Mass Number

The rounded atomic mass number that is used to talk about a specific atom of that element.

Isotope

Atoms with same number of protons, the same element, but different number of neutrons.

Radioactive Decay

The process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element.

Half Life

The length of time required for half of the radioactive atoms in a sample to decay.

Carbon Dating

A scientific method used to determine the age of an artifact using isotopes of Carbon.

Valence Electrons

The electrons found in the outermost shell/farthest away from the nucleus of an atom.

Chemical Bonds

Attractions that occur between atoms to ensure that outer/valence shells are filled.

Ionic Bond

A strong bond that is formed when one or more electrons are transferred from one atom to another and oppositely charged ions attract. Creates salts.

Ion

A charged atom formed from the loss or gain

of electrons to fill valence shells.

Covalent Bond

A strong chemical bond in which two atoms share one or more pairs of outer electrons.

Molecule

Two or more atoms held together by a covalent bond.

Molecular Formula

A formula that shows the types and numbers of atoms combined using chemical symbols and subscripts.

Single Bond

A covalent bond in which two atoms share one pair of electrons.

Double Bond

A covalent bond in which two pairs of electrons are shared between two atoms.

Triple Bond

A covalent bond in which two atoms share three pairs of electrons.

Structural Formula

A formula that indicates the all of the bonds between atoms in a molecule as well as unshared electrons present.

Electronegative

The tendency of an atom to attract electrons (even within a covalent bond).

Polar Covalent Bond

A covalent bond in which electrons are not shared equally between atoms.

Hydrogen Bond

A type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule.

Cohesion

Attraction between molecules of the same substance.

Adhesion

An attraction between molecules of different substances.

Heat

The energy that added that speeds up molecules.

Temperature

The measure of how fast molecules are moving.

Surface Tension

A measure of how difficult it is to stretch or break the surface of a liquid.

Acid

A substance that donates the Hydrogen ion to a solution and occupies the range of 0 - <7 on the pH scale.

Base

A substance that accepts Hydrogen and removes it from solution and occupies the range of >7 - 14 on the pH scale.

Neutral

A substance that has a pH of 7.

pH scale

A system used to describe the acidity or basicity of a solution.

Product

A substance produced in a chemical reaction.

Reactant

A chemical substance that is present at the start of a chemical reaction.

Cation

A positively charged ion (metal)

Anion

A negatively charges atom (nonmetal)

Electron Configuration

the arrangement of electrons in an atom