Periodic Table

Atomic number

Tells the number of p+ in an atom of the element; used to identify an element.

Element symbol

Abbreviation for the name of the element.

Element name

The name of the element.

Atomic mass

The mass of an atom in grams is extremely small; instead we use Atomic Mass Units (amu).

Atomic Mass Unit (amu)

One amu is equal to about 1.66 x 10-27 kg.

Mass number

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

Periodic table

The organization of the modern periodic table is based on atomic number and chemical properties.

Categories of elements

1. State: solid, liquid, gas; 2. Occurrence in nature; 3. General properties: metal, nonmetal, metalloid.

Metals

Shiny, silvery solids that are good conductors of heat and electricity, malleable and ductile.

Nonmetals

Gases or dull brittle solids that are poor conductors.

Metalloids

Solids that are semi-conductors with physical properties like metals and chemical properties like nonmetals.

Periods

The horizontal rows on the periodic table; all elements in the same period have the same number of energy levels in their electron cloud.

Protons

Positively charged particles in the nucleus of an atom.

Neutrons

Neutral particles in the nucleus of an atom.

Electrons

Negatively charged particles that surround the nucleus of an atom.

Electron cloud

The region surrounding the nucleus of an atom where electrons are likely to be found.

Henry Moseley

Scientist known for arranging the periodic table by atomic number.

Chemical properties

Characteristics of a substance that become evident during a chemical reaction.

Physical properties

Characteristics of a substance that can be observed without changing its composition.

Occurrence in nature

Refers to whether elements are found naturally or synthesized.

Ductile

Ability of a material to be stretched into a wire.

Malleable

Ability of a material to be hammered or pressed into shape without breaking.

Groups

The vertical columns on the periodic table.

Valence Electrons

Electrons in an atom's outermost energy level in the electron cloud.

Energy Levels

Shells that hold a certain number of electrons.

Level 1

Holds a maximum of 2 electrons.

Level 2

Holds up to 8 electrons.

Level 3

Holds up to 18 electrons (8 electrons for our purposes).

Level 4

Holds up to 32 electrons (16 electrons for our purposes).

Group 1

Contains elements with 1 valence electron.

Group 2

Contains elements with 2 valence electrons.

Group 13

Contains elements with 3 valence electrons.

Group 14

Contains elements with 4 valence electrons.

Group 18

Contains elements with 8 valence electrons, except for Helium which has 2.

Alkali Metals

Group 1 elements, which are the most reactive metals.

Alkaline Earth Metals

Group 2 elements.

Rare Earth Metals

Group 3 elements.

Transition Metals

Elements in groups 3-12.

Boron Family

Group 13 elements.

Carbon Family

Group 14 elements.

Nitrogen Family

Group 15 elements.

Oxygen Family

Group 16 elements.

Halogens

Group 17 elements, which are the most reactive nonmetals.

Noble Gases

Group 18 elements, which are nonreactive due to being chemically stable.

Bohr Model

Simple diagrams that show the atomic structure of an atom.

Energy Level Notation

Notation representing the distribution of electrons in energy levels, e.g., 2, 5.