Chapter 5 Vocab

periodic law

There is a periodic repetition of chemical and physical properties of elements that are arranged by increasing atomic number.

groups

The columns that elements of the periodic table are in.

periods

The rows that elements of the periodic table are in.

representative elements

The main groups of elements; 1, 2, and 13 to 18.

transition elements

Elements in groups 3 to 12 between the representative elements.

metals

Elements that are generally shiny when smooth and clean, solid at room temperature, and good conductors of heat and electricity

alkali metals

Group 1 elements (except for hydrogen).

alkali-earth metals

Elements in groups 2 of the periodic table.

lanthanide series

A rare subset of inner transition metals.

actinide series

A subset of inner transition metals, many of which are radioactive and used in nuclear energy.

nonmetals

Elements that are generally gases or brittle, dull looking solids.

halogens

Highly reactive elements in group 17.

noble gases

Extremely unreactive group 18 elements.

metalloids

Elements that border the staircase line on the periodic table and that have physical and chemical properties of both metals and nonmetals.

atomic radius

Half the distance between the nuclei of two adjacent or bonded atoms or the distance from the nuclei to the atom’s outermost electron shell.

ion

An atom or a bonded group of atoms that has a positive or negative charge.

ionization energy

The energy required to remove an electron from a gaseous atom.

octet rule

Atoms tend to gain, lose, or share electrons in order to acquire a full set of eight valence electrons.

electronegativity

The ability of an atom to attract shared electrons in a chemical bond.