Atom Vocabulary

Atom

The smallest particle of an element

the building blocks of all matter

Element Is a substance that cannot be broken down

into simpler substances

Sodium atom

Subatomic particle particles smaller than the atom parts of the atom there are three main subatomic particles

Protons Neutrons Electrons

Proton a subatomic particle

found in the nucleus of the atom

has a positive electrical charge

has a mass of 1 amu used to help find the mass of an atom used to help find the charge of an atom determines the identity of an atom

Neutron a subatomic particle of the atom found in the

nucleus has no electrical charge (neutral) has a mass of 1 amu used to help find the

mass of the atom has no effect on the

charge of the atom a different number of neutrons makes a

different isotope of the same element

Electron a subatomic particle found

outside of the nucleus in the electron cloud

has a negative electrical charge is 1/1600th the size of a proton or neutron does NOT affect the mass of the atom is used in determining the charge of an atom

Nucleus a region located in the

center of the atom contains protons and

neutrons contains the mass of the

atom it has a positive electrical

charge held together by strong

nuclear force

Electron cloud a region surrounding the

nucleus of an atom where electrons are likely to be found

is mainly empty space is negatively charged is arranged in energy levels

called shells or orbitals

Valence Electrons

the electrons found on the outermost energy level of an atom

most importantin determiningan element’schemical properties andreactivity

Atomic Number Number of protons in the nucleus of an atom

of an element

Atomic Mass or Mass Number The total number of protons and neutrons in

the nucleus of an atom Mass (of an atom) = protons + neutrons unit is amu (atomic mass unit)

Ion An atom that has gained or lost electrons and

has a charge

Anion A type of ion when an atom gains electrons

and becomes negatively charged

Cation A type of ion when an atom loses electrons

and becomes positively charged

Isotopes Atoms of the same element, but having a

different numbers of neutrons in their nucleus Isotopes will have the same number of

protons (same element), but a different number of neutrons(different mass)

Atoms, Elements, Periodic Table

Groups Vertical columns in the periodic table. All elements in a group have the same

number of electrons in their outer orbital

Periods Horizontal rows in the periodic table. All elements in a period have the same

number of atomic orbitals

Metals Elements that are good conductors of

electricity and heat. Found left of “stairs”

Alkali Metals Group 1 (minus

Hydrogen) Metals with one valence

electron

Alkaline Earth Metals Group 2 Metals with 2 valence electrons

Transition Metals Groups 3-12 Elements that have valence electrons at 2

different energy levels.

Nonmetals Elements that are poor conductors of

electricity and heat. Found to the right of “stairs”

Metalloids Semi-metals Physical properties of both metals and

nonmetals.

Halogens Group 17 Nonmetals with 7 valence electrons

Noble Gases Group 18; 8 Valence electrons Except Helium (has 2 valence electrons) Full valence shell- not very reactive

Properties of Matter

Molecule Particle that is made up of 2 or more atoms

of the same element.

Compound Substance made up of the combined atoms

of 2 or more elements.

Mixture Contains 2 or more types of substances and

does not form a new compound after mixing; maintains individual properties.

Colloid A mixture of substances in which one of the

substances is suspended within the other as small, non-dissolved particles.

Ex: hairspray (aerosols), foams (whipped cream), gels, butter.

Mixing to make butter Butter

Solution Homogeneous

mixture in which one substance is dissolved in another substance

The ocean is a solution.

Solute A substance that is dissolved into another

Salt is a solute.

Solvent A liquid or gas that another substance

dissolves in

Water is a solvent

Physical Property Characteristics of a substance that can be

observed or measured without changing the substance Size, shape, color, density, melting point, boiling

point, volume

Chemical Property Properties of matter that become evident

during a chemical reaction

Precipitate A solid formed by mixing two liquids

A yellow solid precipitate forms

from the mixture of two clear liquids: potassium iodide and lead nitrate.

Corrosiveness A substance that can cause damage to

another that is irreversible.

Flammability A measure of the extent to which a material

will support combustion

Oxidation The combination of a substance with

oxygen. A reaction in which the atoms in an element

lose electrons

Luster The appearance of a mineral surface judged

by its brilliance and ability to reflect light.

Viscosity Measure of a liquid’s resistance to flow