Chemistry Chapter 5

the smallest particle of a chemical element that can exist.

a stable subatomic particle with a charge of negative electricity, found in all atoms

Any of various units of matter below the size of an atom

The nucleus is the very dense region consisting of protons and neutrons at the center of an atom.

a stable subatomic particle occurring in all atomic nuclei, with a positive electric

a subatomic particle of about the same mass as a proton but without an electric charge

A possible level of energy an electron can have

• the number of protons in the nucleus of an atom, which is characteristic of a chemical element and determines its place in the periodic table.

the total number of protons and neutrons in a nucleus.

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei

A model of the atom atom in which a central positive nucleus is surrounded by electrons in energy levels

• The average mass of the naturally occurring isotopes of an element

a table of the chemical elements arranged in order of atomic number

An element that is hard, shiny, malleable, and a good conductor of heat and electricity

Element that is not shiny, malleable, and is a poor conductor of heat and electricity

an element (e.g. arsenic, antimony, or tin) whose properties are intermediate between those of metals and solid non-metals or semiconductors.

A horizontal row of elements in the periodic table

A vertical column of elements in the periodic table

any of the elements lithium, sodium, potassium, rubidium, caesium, and francium, occupying Group 1 of the periodic table. They are very reactive.

any of the elements beryllium, magnesium, calcium, strontium, barium, and radium, occupying Group 2 of the periodic table. They are reactive, electropositive, divalent metals, and form basic oxides which react with water to form comparatively insoluble hydroxides.

any of the elements fluorine, chlorine, bromine, iodine, and astatine, occupying group VIIA (17) of the periodic table. They are reactive non-metallic elements which form strongly acidic compounds with hydrogen from which simple salts can be made.

any of a group of rare gases that include helium, neon, argon, krypton, xenon, and usually radon and that exhibit great stability and extremely low reaction rates

a single electron or one of two or more electrons in the outer shell of an atom that is responsible for the chemical properties of the atom