CHEMISTRY REGENTS HELP

What is chemistry?

The study of matter and how it changes.

What is density?

Mass divided by volume.

What units are commonly used for density?

g/mL or g/L.

What is dimensional analysis?

A method of converting units using conversion factors.

Which zeros are significant?

Sandwiched zeros and ending zeros with a decimal point.

What does a negative exponent in scientific notation mean?

The number is smaller than 1.

What is a physical property?

A property observed without changing composition.

What is a chemical property?

A property describing a substance's ability to undergo chemical change.

Which phase changes absorb energy?

Melting, evaporation, sublimation.

Which phase changes release energy?

Freezing, condensation, deposition.

During a phase change, what stays constant?

Temperature and average kinetic energy.

What equation is used for calorimetry?

Q = mCΔT.

What equation is used for heat of fusion?

Q = mHf.

What equation is used for heat of vaporization?

Q = mHv.

What does Kinetic Molecular Theory state?

Gas particles move constantly and randomly.

Boyle's Law relationship?

Pressure and volume are inversely related.

Charles's Law relationship?

Volume and temperature are directly related.

Gay-Lussac's Law relationship?

Pressure and temperature are directly related.

What temperature unit must be used in gas laws?

Kelvin.

At STP, one mole of gas occupies what volume?

22.4 L.

What happens to vapor pressure when intermolecular forces are weak?

Vapor pressure increases.

Who proposed the Gold Foil Experiment?

Ernest Rutherford.

What did Rutherford discover?

Atoms are mostly empty space with a dense positive nucleus.

Charge of a proton?

+1.

Charge of a neutron?

0.

Charge of an electron?

-1.

Atomic number equals what?

Number of protons.

Mass number equals what?

Protons + neutrons.

What is an isotope?

Same element, different number of neutrons.

What is a cation?

Positive ion formed by losing electrons.

What is an anion?

Negative ion formed by gaining electrons.

Periods run which direction?

Horizontal.

Groups run which direction?

Vertical.

What trend increases left and down?

Atomic radius and metallic character.

What trend increases right and up?

Electronegativity and ionization energy.

Most electronegative element?

Fluorine.

Group 1 elements?

Alkali metals.

Group 17 elements?

Halogens.

Group 18 elements?

Noble gases.

Ionic bonds occur between what types of elements?

Metals and nonmetals.

Covalent bonds occur between what types of elements?

Two nonmetals.

Metallic bonding involves what?

A sea of mobile electrons.

What is a polar covalent bond?

Unequal sharing of electrons.

What is a nonpolar covalent bond?

Equal sharing of electrons.

Strongest IMF?

Hydrogen bonding.

Hydrogen bonding occurs with H bonded to what three elements?

F, O, or N.

How many particles are in 1 mole?

6.02 × 10²³.

Volume of 1 mole of gas at STP?

22.4 L.

What law states matter cannot be created or destroyed?

Law of Conservation of Matter.

Five reaction types?

Synthesis, decomposition, single replacement, double replacement, combustion.

What is a hydrocarbon?

Compound containing only carbon and hydrogen.

What is the solute?

Substance being dissolved.

What is the solvent?

Substance doing the dissolving.

What is a saturated solution?

Cannot dissolve more solute.

What is an unsaturated solution?

Can dissolve more solute.

What is a supersaturated solution?

Contains more dissolved solute than normally possible.

What does Table G show?

Solubility curves.

What does Table F show?

Solubility rules.

What is activation energy?

Minimum energy required for a reaction to occur.

What does a catalyst do?

Lowers activation energy.

What is an exothermic reaction?

Releases energy.

What is an endothermic reaction?

Absorbs energy.

At equilibrium, what is true about reaction rates?

Forward rate = reverse rate.

What principle explains shifts in equilibrium?

Le Chatelier's Principle.

pH less than 7 means?

Acidic.

pH greater than 7 means?

Basic.

pH of a neutral solution?

7.

Acids are proton __________?

Donors.

Bases are proton __________?

Acceptors.

Products of neutralization?

Salt and water.

LEO says what?

Loss of Electrons = Oxidation.

GER says what?

Gain of Electrons = Reduction.

Where does oxidation occur?

Anode.

Where does reduction occur?

Cathode.

What mnemonic helps remember this?

AN OX, RED CAT.

What is an alkane?

Hydrocarbon with only single bonds.

What is an alkene?

Hydrocarbon with a double bond.

What is an alkyne?

Hydrocarbon with a triple bond.

What are isomers?

Same molecular formula, different structures.

What must carbon always form?

Four bonds.

What is a radioisotope?

An unstable isotope that undergoes decay.

What is alpha decay?

Release of a helium nucleus.

What is beta decay?

Release of an electron.

What is gamma decay?

Release of energy only.

What is half-life?

Time needed for half of a radioactive sample to decay.

Difference between fission and fusion?

Fission splits nuclei; fusion combines nuclei.