Chemistry Regents Must Know Facts

Substitute the word "" for "average kinetic energy" to make questions easier.

temperature

Substances that undergo sublimation, change from a directly to a due to weak IMFs.

solid, gas

Solutions containing ions of transition elements (groups ) are often .

3–12, colored

Only two elements exist as liquids at STP: (non-metal) and (metal).

Br, Hg

Elements are arranged in the periodic table according to their .

atomic number

The atomic mass of an element is the average of the element’s naturally occurring isotopes.

weighted

An orbital is defined as a region of space where there is a high probability of finding an .

electron

The mass # of an atom is found by adding the number of and .

protons, neutrons

The nuclear charge of an atom is the same as its number of .

protons

Molecular substances contain bonds, have m.p.'s, and are .

covalent, low, soft

Network solids contain bonds and have m.p.'s and are .

covalent, high, hard

Ionic solids have a structure and do not conduct electricity unless or .

crystal lattice, molten, aqueous

Molecules with polar bonds may be non-dipoles because their shapes are .

symmetrical

Energy is when bonds are broken, and when bonds are formed.

absorbed, released

The 7 diatomic elements are .

BrINClHOF

1 mole = molecules = L at STP = g (GFM)

6.02 × 10²³, 22.4, gram formula mass

Water, NH₃, and HF have unusually high boiling points due to bonding.

hydrogen

Elements in the same group have the same number of electrons.

valence

Elements in the same period have the same number of levels.

energy

Atoms that lose electrons in size and become ions.

decrease, positive

Metallic elements generally obtain a complete octet by electrons.

losing

The most metallic elements are located in the of the periodic table.

lower left

Metals are good conductors of electricity and heat because of their "."

sea of mobile electrons

Group 1 & 2 metals are so reactive they must be obtained by .

electrolysis

Semi-metals are located and exhibit and properties.

along the staircase, metallic, nonmetallic

Gases behave most like ideal gases at temperature and pressure.

high, low

The two gases that behave most like ideal gases are and .

hydrogen, helium

An electrolyte conducts electricity in water because it produces .

ions

Three examples of electrolytes are , , and .

acids, bases, salts

Arrhenius acids yield ions in solution; bases yield ions.

H⁺, OH⁻

A pH decrease of 2 indicates the solution has become acidic.

100 times more

Salts contain bonds and are made of a and a .

ionic, metal, nonmetal

LEO stands for ; GER stands for .

Lose Electrons = Oxidation, Gain Electrons = Reduction

RED CAT = ; AN OX = .

Reduction at cathode, Oxidation at anode

An electrolytic cell requires a(n) to operate.

external power source

Saturated hydrocarbons contain only bonds.

single

Larger hydrocarbons have boiling points than smaller ones due to stronger IMFs.

higher

Reactions are spontaneous when they are and increase in .

exothermic, entropy

Entropy increases from to to .

solid, liquid, gas

In redox reactions, and must be conserved.

mass, charge

One element changing into another is called .

transmutation

All elements with atomic numbers greater than are radioactive.

83

Alpha & Beta decay are types of transmutation.

natural

Half-life is the time it takes for a sample to decay to its mass.

half

Fission and fusion release energy by converting to .

mass, energy

Polar solutes dissolve best in solvents.

polar

As solute concentration increases, boiling point .

increases

Ionic solutes affect boiling/melting point more than molecular ones because they in water.

dissociate

Electrons far from the nucleus have energy.

more

Electrons emit energy when returning from to state.

excited, ground

Rutherford’s experiment showed the atom is mostly .

empty space

Equilibrium occurs when forward and reverse reaction are equal.

rates

At equilibrium, reactant and product concentrations are .

constant

Electronegativity measures an atom’s attraction for .

electrons

Ionization energy is the energy needed to an electron.

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