Atoms, the Periodic Table, and Classification of Matter

Flashcards reviewing the structure of atoms, the periodic table, and properties of matter.

Atom

The smallest particle of an element that retains the element's properties.

Nucleus

The small, positively charged center of an atom.

Protons

Particles in the nucleus with an electric charge of 1+.

Neutrons

Electrically neutral particles in the nucleus; they do not have a charge.

Electrons

Particles with an electric charge of 1-.

Quarks

Protons and neutrons are composed of these smaller particles.

Electron cloud

Area around the nucleus of an atom where electrons are most likely to be found.

Chemical symbol

A short or abbreviated name of an element.

Element

Matter that is composed of only one type of atom.

Electron cloud

The space surrounding the nucleus occupied by electrons.

Atomic number

The number of protons in an atom's nucleus.

Mass number

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

Isotopes

Atoms of the same element that have different numbers of neutrons.

Average atomic mass

Weighted average mass of all naturally occurring isotopes of an element, measured in atomic mass units (amu).

Periodic table

Organized list of all known elements that are arranged by increasing atomic number and by changes in chemical and physical properties.

Chemical property

Any characteristic of a substance that indicates whether it can undergo a certain chemical change.

Periods

Rows of elements (horizontal) in the periodic table.

Groups/Families

Columns of elements (vertical) in the periodic table.

Valence electrons

Electrons in an element's outermost energy level.

Property

Characteristic or essential quality of matter.

Substance

Type of matter with a fixed composition.

Element

Substance made up of atoms that are all alike.

Compound

Substance in which the atoms of two or more elements are chemically combined in a fixed proportion.

Heterogeneous mixture

Mixture in which different materials remain distinct.

Suspension

Heterogeneous mixture made of a liquid and solid particles that settle.

Colloid

Heterogeneous mixture with particles that never settle.

Tyndall effect

Scattering of a light beam as it passes through a colloid.

Homogeneous mixture

Mixture that remains constantly and uniformly mixed and has particles that are so small that they cannot be seen with a microscope.

Solution

Same thing as a homogeneous mixture.

Boiling point

Temperature at which the vapor pressure of the liquid is equal to the external pressure acting on the surface of the liquid

Physical property

Any characteristic of a material that you can observe without changing the identity of the substance

Physical change

A change in size, shape, or state of matter in which the identity of the substance remains the same

Distillation

Process of separating substances, such as salt and water, in a mixture by evaporating a liquid and recondensing its vapor

Chemical property

Any characteristic of a material that you can observe that produces one or more new substances

Chemical change

A change of one substance to another

Law of conservation of mass

Mass of all substances that are present before a chemical change equals the mass of all the substances that remain after the change