is a pure substance that cannot be broken down into simpler substances by a chemical reaction.
located on the left side of the periodic table and include 2 transition rows at the bottom. They are shiny solids that are good conductors of heat and electricity. All of them are solids at room temperature except for mercury, which is liquid.
do not have a shiny appearance, and they are generally poor conductors of electricity. They like sulfur and carbon are solids at room temperature.
have properties intermediate between metals and nonmetals. Only seven elements are categorized as this kind of element.
oxygen, carbon, hydrogen and nitrogen
Comprise 96% of the mass of the human body and are known as the building block elements
consists of element symbols to show the identity of the elements forming a compound and subscripts to show the ratio of atoms (the building blocks of matter) contained in the compound.
is a subatomic particle that holds a positive charge in an atom and is symbolized by p and has a charge that is = +1
is a subatomic particle that holds a negative charge in an atom and is symbolized by e-and has a charge that is = -1
is a subatomic particle that holds no charge in an atom and therefore has a charge that is = 0
a dense core that contains the protons and neutrons. Most of the mass of the atom resides here.
is composed of electrons that move rapidly in the almost empty space surrounding the nucleus. This comprises most of the volume of an atom.
Atomic Number (Z)
tells us both the number of protons in the nucleus and the number of electrons in the electron cloud of a neutral atom.