anything that takes up space and has mass
substance that cannot be broken down to other substances by ordinary chemical means (Oxygen, Hydrogen, Carbon, etc.)
are needed by all forms of life, but only in tiny amounts. (Fe, for example)
a substance consisting of two or more different elements combined in a fixed ratio (NaCl)
subatomic particle with a single positive electrical charge
electrically neutral - has no electrical charge
atom's central core
unique number of protons to each element
sum of protons and neutrons in its nucleus
(or weight) normally approximately equal to its mass number
of an element have the same number of protons and electrons and behave identically in chemical reactions, but have a different number of neutrons.
nucleus decays spontaneously, giving off particles and energy
electrons only occur at these levels
attractions that cause atoms to stay close together
when opposite charges attract each other and the attractions hold them together
ionic compound, sodium chloride for example.
two or more atoms held together by a covalent bonds
indicated by a pair of lines. An O2 molecule has the two oxygen atoms sharing two pairs of electrons, for example.
attraction for shared electrons
Nonpolar covalent bonds
electrons are shared equally between the atoms
unequal distribution of charges
clinging of one substance to another
smallest particle of an element
electrons on the outermost energy level of an atom
outermost electron shell
a region in an atom where there is a high probability of finding electrons
A covalent bond in which one electron pair is shared by two atoms.
when two atoms share two pair of valence electrons
A type of molecular notation in which the constituent atoms are joined by lines representing covalent bonds.
a chemical formula that shows the number and kinds of atoms in a molecule, but not the arrangement of the atoms.
polar covalent bond
A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.
very weak bonds; occurs when a hydrogen atom in one molecule is attracted to the electrostatic atom in another molecule
van der waals interactions
Attractions between molecules that are close together as a result of positive and negative charges, collectively these interactions can be strong; example: gecko's toe hairs and a wall surface
process that changes one set of chemicals into another set of chemicals