chem regents

Rutherord- atoms were mostly empty space

with small, dense positively charged nucleus.

Bohr Model - Small, dense, positively

charged nucleus surrounded by electrons in circular orbits.

Protons and neutrons are found

in the nucleus.

The number of protons in an atom equals

the number of electrons.

The mass of a proton and nuetron is

1 amu

The mass of an electron

n is almost 0 amu.

Each electron in an atom has its own distinct amount of

energy

. The outermost electrons are called

valence electrons.

atoms with equal numbers of protons but different numbers of neutrons

are called isotopes

The average atomic mass of an element is the

weighted average of its naturally occurring isotopes.

Transmutation

A change in the nucleus of an atom changes it to a new type of atom

Spontaneous decay can involve the release of different particles from the

nucleus

Chemical compounds are formed when

atoms are bonded together.

Ionic substances have

high melting and boiling points, form crystals, dissolve in water (dissociation), and conduct electricity in solution and as a liquid.

Covalent or molecular substances have

lower melting and boiling points, do not conduct electricity

. Chemical bonds are formed when valence electrons are

ionic,covalent, and metallic

In multiple (double or triple) covalent bonds more than

1 pair of electrons are shared between two atoms.

Polarity of a molecule can be determined by its

shape and the distribution of the charge.

When an atom loses an electron

it becomes a positive ion and its radius decreases.

When an atom gains an electron,

it becomes a negative ion and its radius increases.

. Electronegativity indicates

how strongly an atom of an element attracts electrons in a chemical bond. These values are based on an arbitrary scale.

0.0 - 0.4 =

non-polar covalent

0.4-1.7 =

polar covalent

1.7+ =

ionic

Metals react with nonmetals to form

ionic compounds.

Nonmetals bond with nonmetals to form

covalent compounds (molecules).

Ionic compounds with polyatomic ions have

both ionic and covalent bonds.

 Filtration and distillation are examples of processes used to

separate mixtures.

. Heat of fusion (Hf)is

the energy needed to convert one gram of a substance from solid to liquid.

Heat of vaporization (Hv) is the

energy needed to convert one gram of a substance from liquid to gas.

Increasing pressure causes

a decrease in volume

Increasing temperature causes an

increase in volume

Increasing temperature causes

an increase in pressure.

A real gas is most like an ideal gas when

it is at low temperature and high pressure.

Equal volumes of gasses at the same temp and pressure

have an equal number of particles.

The Law of Conservation of Energy states that energy can not be

lost or destroyed, only changed from one form to another.

Temperature is

a measure of the average kinetic energy of the particles in a sample

Elements are arranged in order of increasing

atomic number.

The atomic mass is the sum of

protons and neutrons in the nucleus

Isotopes of an element are identified by

the sum of protons and neutrons.

Isotopes of the same element have the

same number of protons and a different number of neutrons.

. Elements may be differentiated by

their physical n chemical properties

Ex of physical: Density, conductivity, malleability, hardness, ductility, solubility

Elements of the same period

have the same number of occupied energy levels.

Group 1 elements other than H

alkali metals.

Group 2 elements

alkali earth metals.

Group 17 elements are

halogens.

Group 18 elements are

noble or inert gasses

All chemical reactions show

a conservation of mass, energy and charge.

A balanced chemical equation represents

conservation of atoms.

Solubility depends on

temperature, pressure, and the nature of the solute and solvent.

2. Ionic substances dissolve

in polar solvents.

Adding a solute to a solvent causes the boiling point of the solvent to ___ and the freezing point to _____

Increase

decrease

. Collision theory states that a reaction is most likely to occur

if reactant particles collide with the proper energy and orientation.

At equilibrium the rate of the forward reaction equals

the rate of the reverse reaction.

A catalyst provides an alternative pathway for a chemical reaction

The catalyzed reaction requires a lower activation energy than the uncatalyzed reaction.

 Adding a catalyst increases the rate of the forward and reverse reactions equally,

there is no shift in equilibrium.

Entropy is a measure of the

randomness or disorder in a system.

Exothermic reactions that result in increased entropy are

spontaneous.

Arrhenius acids and bases

are electrolytes.

electrolyte

substance which, when dissolved in water, forms a solution capable of conducting electricity

In neutralization

reactions an Arrhenius acid and an Arrhenius base react to form salt and water.

an acid is an

H+ donor

a base an

H+ acceptor.

An oxidation-reduction (redox) reaction involves

the transfer of electrons (e- ).

Reduction is the

gain of electrons and decrease of oxidation number.

. Oxidation is the

loss of electrons and increase of oxidation number.

An electrochemical cell can be either

voltaic or electrolytic.

In an electrochemical cell oxidation occurs

at the anode and reduction at the cathode.

electrolysis.

. An electrolytic cell requires energy to produce a chemical change

6. Isomers of organic compounds have

the same molecular formula but different structures and properties.