Everything for the Chemistry Regents

What are atoms?

Smallest unit of matter

What is the structure of an atom?

Central nucleus with orbiting electrons

What is in the nucleus of an atom?

Protons and neutrons

What are the charges of protons, neutrons, and electrons?

Protons are positive, neutrons are neutral, electrons are negative

What is the mass of a proton?

1 amu

What is the mass of a neutron?

1 amu

What is the mass of an electron?

0 amu (1/1836 of a proton)

What is the overall charge of the nucleus?

Positive

What are isotopes?

Atoms with the same atomic number but different atomic masses

What are the three common isotopes of hydrogen?

Protium, Deuterium, and Tritium

What is the difference between the three isotopes of hydrogen?

Different number of neutrons

What is unique about Tritium?

It is radioactive

What is mass number?

Sum of protons and neutrons

What is atomic mass?

Weighted average of all isotopes of an element

What is Bohr's model of the atom?

A simple model of the atom

What are the energy levels in Bohr's model named?

K, L, M, N, O, P, etc. or numbered 1, 2, 3, 4, 5, etc.

What are the energy levels also known as?

Principal quantum numbers

How many electrons can each orbital hold?

2 electrons

What happens when electrons return to their normal energy levels?

They give off distinct colors (spectral lines)

What is the valence shell?

The last/highest energy level with electrons in it

What is an atom's kernel?

The nucleus and all energy levels except the valence energy level

What is the Periodic Table of the elements?

An organized chart of all known elements

What is the basis for the arrangement of elements on the periodic chart?

Atomic number (increasing nuclear charge)

What are the three classifications of elements?

Metals, nonmetals, metalloids

What are metalloids?

Elements with properties of both metals and nonmetals

How can elements be grouped?

By their valence shell electron number

Which elements are metals?

Elements with 1, 2, and/or 3 valence shell electrons

Which elements are nonmetals?

Elements with 5, 6, and/or 7 valence shell electrons

Where are metalloids located on the periodic chart?

Along the 'staircase' boundary between metals and nonmetals

What group are noble gases in?

Group 18

How many valence shell electrons do noble gases have?

8 (except Helium, which has 2)

What do vertical groups (columns) of elements display?

Similar chemical properties

What are horizontal rows called?

Periods

How do properties change across a period?

Slowly from metallic to nonmetallic

What does the period (row) number represent?

The number of occupied principal energy levels for a given element

What is atomic radius?

The closest distance to which one atom can approach another of the same type of atom

What is covalent radius?

The distance from the center of the nucleus to the outer valence shell of that atom (or, half the distance between two covalently bonded atoms of the same element)

Are ionic radii of metals larger or smaller than their atomic radii?

Smaller (lose electrons)

Are ionic radii of nonmetals larger or smaller than their atomic radii?

Larger (gain electrons)

What is electronegativity?

A measure of the ability of an atom to attract another atom's electrons while in a chemical bond

Do metals generally have high or low electronegativities?

Low (give away electrons)

Do nonmetals generally have high or low electronegativities?

High (gain electrons)

What element has the highest electronegativity value of all elements?

Fluorine (4.0)

What element has the greatest attraction for electrons?

Fluorine

What is electronegativity?

Ability of an atom to attract electrons

What is the range of electronegativity difference for a nonpolar covalent bond?

0 to 0.3

What is the range of electronegativity difference for a polar covalent bond?

0.3 to 1.7

What is the range of electronegativity difference for an ionic bond?

\> 1.7

What are the two most common bond types?

Ionic and covalent bonds

What is a nonzero charge?

A charge that is not zero.

What is the oxidation number of oxygen?

-2 except in peroxides (-1) or bonded to a halogen (+2).

What is the oxidation number of hydrogen?

+1 except in metal hydrides (-1).

What are binary compounds?

Compounds with two different types of elements in the formula.

What are ternary compounds?

Compounds with three different elements in the formula.

What are polyatomic ions?

Ions with a net charge either positive or negative.

When do you use a roman numeral in naming compounds?

When the positive element has more than one positive choice.

What are binary acids?

Acids with only two different elements.

What are ternary acids?

Acids with three different elements.

What are chemical equations?

Statements of a reaction.

Why must chemical equations be balanced?

To follow the Law of Conservation of Mass.

What should you manipulate/change when balancing a chemical equation?

Coefficients.

What is the mole unit used for?

Counting atoms and molecules.

What is Avogadro's number?

6.022 x 10^23.

What is the mass of one mole of any substance?

The sum of the atomic weights composing the substance.

What is gram atomic mass?

The mass in grams of a mole of atoms.

What is gram formula mass?

The sum of the masses of a molecule.

What is the volume of one mole of any gas at STP?

22.4 liters.

What is stoichiometry?

A study of the molar proportions.

What is percent composition?

The relative percentages of each element in a formula.

What are the 5 basic reaction types?

Single replacement, double replacement, synthesis, decomposition and combustion.

What are ionic bonds?

Bonds between atoms when electrons are transferred (electronegativity difference 1.7 or greater).

What are some characteristics of ionically bonded substances?

High melting points, geometric structure of solid ionic crystals (called "crystal lattice"), and they do not conduct electricity as solids but will conduct if melted or dissolved in water.

What are covalent bonds?

Substances that share electrons.

What are polar covalent bonds?

Covalent substances that share electrons unequally (electronegativity difference \> 0.3 but less than 1.7).

What is the electronegativity difference in nonpolar substances?

0.0 to 0.3.

What are some examples of coordinate covalent substances?

NH4+ ("ammonium ion") and H3O+ ("hydronium ion").

What are molecular substances?

Discrete particles formed from covalently bonded atoms.

What are the states of molecular substances?

Liquids, solids or gases.

What are the properties of molecular substances?

Good insulators, poor conductors of heat and electricity, low melting points.

What are network solids?

Covalent bonds in a giant, repeating macromolecule network.

What are the properties of network solids?

Hard, poor electrical and heat conductors, very high melting points.

What are some examples of network solids?

Diamond, graphite, silicon carbide, silicon dioxide.

What is metallic bonding?

Bonding between atoms of metals with small numbers of valence electrons.

What is the structure of metallic bonds?

Regular arrangement of positive ions in a crystal lattice immersed in a sea of mobile electrons.

What happens to an atom's size when it gains or loses electrons?

It changes; increases when gaining, decreases when losing.

What happens to the size of metals when they lose electrons?

They have smaller radii than they did as neutral atoms.

What happens to the size of nonmetals when they gain electrons?

They have larger ionic radii than they did as neutral atoms.

What are intermolecular forces?

Attractions between neighboring atoms/molecules.

What is the difference between intermolecular forces and bonds?

Bonds hold a molecule together, while IMF's are between neighboring molecules.

What are some examples of intermolecular forces?

Dipole-dipole attractions, hydrogen bonding, Van der Waals/London forces, ion-molecule attractions.

What are dipole-dipole attractions?

Attractions between the negative end of a polar molecule and the positive end of another polar molecule of the same type.

What are hydrogen bonds?

Bonds formed between molecules when hydrogen is covalently bonded to an element of small radius.

What are FON bonds?

Common bonds with hydrogen, oxygen, fluorine or nitrogen.

What are hydrogen bonds?

Strong attractions between water molecules.

What are Van der Waals forces?

Weak attractions between nonpolar molecules.

What are Molecule-Ion attractions?

Attractions between an ionic substance and a molecular substance.

What are the three phases of matter?

Solid, liquid and gas.

What is vapor pressure?

Measure of vapor present above a liquid's surface.

What is boiling point?

Temperature at which vapor pressure \= atmospheric pressure.

What is the boiling point of water at 1 atm?

100ºC.