anything that takes up space and has mass (dead or living); matter is made up of elements
elements
is a substance that cannot be
broken down to other substances by chemical reactions (its made up of one type
of atom);
there are 92 elements
occurring in nature
compound
a substance consisting of two or more diff. elements combined in a fixed ratio ex: NaCl (table salt)
trace elements
are those required by an organism only in
minute quantities like Ca P K S
atom
smallest unit of matter that still retains the properties of an
element
neutrons
no electrical charge
protons
positive charge
electrons
negative charge
atomic number
# of protons
mass number
sum of protons plus neutrons in the nucleus
isotopes
different atomic mass but same element
radioactive isotopes
one which the nucleus decays
spontaneously, giving off particles and energy
energy
the capacity to cause change
electron shells
charac. Avg. distance and
energy level; The chem. Behavior of an atom depends mostly on the number of electrons in its outermost shell
inert
means that the atom is not chemically reactive
orbital
the 3-D space where an electron is found 90% of the time
covalent bond
sharing a pair of valance electrons by two atoms
molecule
two or more atoms held together by covalent bonds
Lewis dot structure
H:H ( 2 hydrogen covalent
bond); Molecular formula: H2
electronegativity
the attraction of particular kind of atom
for the electrons of a covalent bond
non polar covalent bond
electrons are shared equally
polar covalent
bond are not shared equally
Oxygen has a partial negative atom “delta minus”
Hydrogen has a partial positive atom “delta plus”
ion
charged molecule or atom
cation
positive charged ion
anion
negative charged ion
ionic bond
when cation and anion attract each other. Opposite attraction Ionic compounds or salt: compounds formed by ionic bonds; Most strongest bond is covalent bond
hydrogen bond
weak chem. Bond forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom
van de waals interaction
weak and occur only when atoms and molecules are very close together