Matter Unit Study Guide

matter
Anything that has mass and takes up space
Properties of Matter
determined by the structure of its atoms and how they are joined
atoms
building blocks of matter
mass
amount of matter in an object
kilograms
measure mass
atomic theory of matter
every substance is made of atoms, there are only a certain number of the kinds of atoms in the universe, in all forms of matter there are only different arrangements of these same kinds of atoms
size of atoms
less than 1 million average atoms side by side is equal to the thickness of paper
Nucleus
small central core in the atom, made of protons and neutrons
proton
positive
atomic number
the number of protons in the nucleus, it identifies the atom and the element
neutron
neutral, adds to mass of an atom
radioactivity
caused by a loss of neutrons
how to find the amount of neutrons
mass number – protons = neutrons
electron energy levels
negative charge, insignificant mass
atomic number =
number of electrons in energy levels
mass number
number of protons and neutrons, round the atomic mass, use it to find neutrons
Atomic mass
average of all mass numbers
isotopes
atom of an element that has the same number of protons as another atom of the same element, but a different number of neutrons
each isotope has its own mass number
pure substance
a substance with constant composition, can be classified as either an element or as a compound (table salt NaCl)
element
a substance that cannot be separated into two or more substances by normal chemical means (or physical means), elements are composed of only one type of atom, example – iron Fe
normal chemicals means
exclude nuclear reactions
compound
a substance that contains two or more elements in definite proportion by weight, the composition of a pure compound will be the same, regardless of the method of preparation,
composed of more than one kind of atom
sodium chloride NaCl
molecule
the smallest unit of a compound that still retains all of the properties of the compound
physical properties and changes
have to do with appearance, they can be observed by your senses and by measuring the length, width, height, mass and density of a substance
examples of physical properties and changes
melting, color change, crumpling
chemical properties and changes
how substances react with other substances a substance will change into something new and different
examples of chemical properties and changes
digestion, combustion, radioactivity
mixtures
two or more substances combined in varying proportions – each retaining its own specific properties
separating components of mixtures
by physical means without making and breaking of chemical bonds
heterogeneous mixture
mixture in which the properties and composition are not uniform throughout the sample (cereal, concrete, party mix)
homogeneous mixture
mixture in which the properties and composition are uniform throughout the sample
solutions
a solute dissolves in a solvent (water is the universal solvent)
solubility
the amount of solute a solvent can dissolve and dependent on temperature
saturated solution
a solvent has dissolved all the solute it can at a certain temperature
rate of solution
causing the solute to dissolve more quickly in the solvent
three ways to increase the rate of dissolving
stirring – moves particle
crushing – exposes more of the solutes surface area to the solvent
heating the solvent-the particles of the solvent are moving more quickly
kinetic molecular theory
matter is made of particles (molecules) that are in constant motion
as thermal energy is added, kinetic energy of particles (temperature) increases
As thermal energy is removed kinetic energy of particles (temperature) decreases
Particles move faster and spread apart as their kinetic energy increases and move more slowly and get closer together as their kinetic energy decreases
State of matter is determined by
kinetic energy of particles
latent heat
amount of energy released or absorbed during a change of state
heat of fusion
heat of fusion is the amount of heat energy needed to change state of matter from a solid into a liquid or vice versa, temperatures remain constant
melting / freezing point
point at which a substance changes from a solid to liquid or vice versa
heat of vaporization
the amount of heat energy needed to change state of matter from a liquid into a gas, or vice versa, temperature remains constant (being absorbed)
boiling point
point at which a substance changes from a liquid to a gas
density
the mass of a substance divided by its volume
density equation
D = m/v
buoyancy
change in density of water