Chem Chapter 2 pt. 2 Notes

Atoms

mostly empty space with a dense center called the nucleus. Even though small, the nucleus contains nearly all the atoms mass.

Subatomic particles

protons, neutrons, and electrons

Protons

located inside the nucleus, charge +1, mass 1 amu

Neutrons

located inside the nucleus, charge of zero, 1 amu

Atomic number

the number of protons inside the nucleus. Unique to each atom. Also the number of electrons in a neutral atom. Located on the periodic table.

Mass number

the sum of protons and neutrons for a specific atom

Ions

atoms that gain or lose electrons creating a charge. Charge written in upper right

Anions

gain electrons and have a negative charge

Cations

lose electrons and have a positive charge

Isotopes

all atoms of a specific element are not identical. The number of neutrons can change in a neutral atom.

Isotopes

atoms with the same number of protons but different number of neutrons. Each isotope has a different isotope mass. Most elements occur in nature as a mixture of isotopes.

Atomic weight or mass of isotopes

weighted average of all isotopes in an element need both the mass and abundance percentage of each isotope

Elemental symbols

symbols on the periodic table made up of one or two letters. First letter is always capitalized second letters always lowercase. Some names come from Latin.

Periodic table terminology

group are columns referred to by group number or by name. Periods are rows look for * or ++

Metals

to the left of the line with the exception of hydrogen, which is a nonmetal. Solids at room temperature except for mercury, which is a liquid. Properties: luster/shiny, high conductivity, malleable (pounded into sheets), ductal(drawn into wires).

Nonmetals

to the right of the line. At room temperature there are six solids (C, P, S, Se, I, At) one liquid (Br) and 11 gases. Properties: the solids are not luster us nor malleable nor ductile and have a low conductivity.

Metalloids/semi metals

the side, touching the line except for aluminum, which is a metal. Has properties of both but more like side is on. ex.) Te is more like a nonmetal because it is to the right