Atom Terms
mixture
2 or more substances which have been combined such that each substance retains its own chemical identity ( ex. Salt water )
Ionic Bond
a chemical link between 2 atoms caused by an electrostatic force between oppositely charged ions in an ionic compound ( Mg +2 + 2 Cl-1 = MgCl2 )
covalent bond
a chemical link between two non metallic atoms in which electrons are shared between them
molecular compound
a compound formed by bonds in which the atoms share one or more pairs of valence electrons. May be a solid, liquid or gas that has electrically neutral atoms held together by chemical bonds in a definite arrangement. Same as covalent compounds.
covalent compound
a compound formed by bonds in which the non metallic atoms share one or more pairs of valence electrons. May the solid, liquid or gas that has electrically neutral atoms held together by chemical bonds in a definite arrangement. Same as Molecular Compounds.
Ionic Compound
a compound formed by ions bonding together through electrostatic forces
electron
a negatively charged component of an atom; exist outside of and surrounding the atom nucleus; carries one unit of negative charge (charge = -1) and has a very small mass ( mass = 1/2000 amu) compared to a proton or neutron
compound
a pure substance composed of two or more different elements whose composition is constant
metal
a solid material that is typically hard, shiny, malleable, fusible and ductile, with good electrical and thermal conductivity ( e.g. iron, silver, copper and alloys such as brass and steel)
element
a substance that cannot be broken down by chemical means; defined by the number of protons (atomic number) they possess
Ion
an atom or molecule with a net electric charge due to the loss or gain of one or more electrons ( Na +1, O -2)
metalloid
an element ( eg germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals. They are electrical semi conductors.
molecular formula
an expression which states the number and type of atoms present in a molecule of a substance ( ex. KNO3 has 1 potassium, 1 nitrogen and 3 oxygen)
mass number
an integer equal to the sum of the number of protons and neutrons of the atomic nucleus
nucleon
another name for the particles that make up an atomic nucleus: protons and neutrons
matter
any type of material; anything that has a mass and takes up space
atomic mass
approximately equivalent to the number of protons and neutrons in the atom ( nucleons / mass number) or to the average allowing for the relative abundances of different isotopes
Isotopes
each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties: in particular, a radioactive form of an element
atomic number
integral number of protons in the nucleus; defines the identity of the element
nucleus
means center; refers to the positively charged center containing protons ( mass = 1 amu, charge +1) and neutron ( mass= 1 amu , no charge)
non metal
one of the elements which do not exhibit metallic properties, generally located in the upper right hand corner of the periodic table. An element incapable of forming simple positive ions in solution
atomic mass unit
one twelfth of a mass of an atom of Carbon-12 isotope; a unit for stating atomic and formula weights: also called dalton. Abbreviated amu
proton
subatomic particle with the symbol p or p+ ( mass = 1 amu, charge +1) . One or more of them are present in the nucleus of each atom.
neutron
the particle in the atomic nucleus with a mass = 1 amu and a charge = 0 (neutral)
mass
the property which reflects the quantity of matter within a sample. It is usually measured in grams or kilograms
atom
the smallest particle of an element in which it still retains its' characteristics
molecule
the smallest physical unit of an element or compound, consisting of one or more like atoms in an element and two or more different atoms in a compound