Fundamentals Of Chemistry Test Questions – Flashcards

The term states of matter refers to the physical forms in which matter exists: solid, liquid, and gas.

The atomic weight of an element is defined as the weighted average of the masses of all of its natural occurring isotopes.

The weight of a molecule, the molecular weight

,

is the total mass of the individual atoms.

One mole represents a definite number of objects, substances, or particles. (For example, a mole of atoms, a mole of ions, a mole of molecules, and even,

theoretically, a mole of elephants.)

A mole is defined as the quantity of a pure substance that contains 6.02 x 10²³

units (atoms, ions, molecules, or elephants) of that substance.

The mass of a mole of atoms is called the gram atomic weight (GAW).

The mass of a mole of molecules is called the molar mass or gram molecular weight (GMW).

An atom is classified chemically by the number of protons in its nucleus (atomic number)

The term valence (of an atom) is defined as the number of electrons an element gains or loses, or the number of pairs of electrons it shares when it interacts with other elements.

The temporary dipole induces a similar temporary dipole on a nearby atom, ion, or molecule. Every instant, billions of these temporary dipoles form, break apart, and reform to act as a weak electrostatic force of attraction known as Van der Waals forces

.

These forces occur between the molecules of nonpolar covalent substances

These forces are generally believed to be caused by a temporary dipole, or unequal charge distribution, as electrons constantly move about in an atom, ion, or molecule.

A covalent bond is formed when one or more electrons from an atom pair off with one or more electrons from another atom and form overlapping electron shells in which both atoms share the paired electrons.

In the metallic bond, an atom achieves a more stable configuration by sharing the electrons in its outer shell with many other atoms.

When the shared pair of electrons is

NOT

shared equally, one end of the bond is positive, and the other end is negative.

The Law of Conservation of Mass - total mass of the products equals the total mass of the reactants

The Law of Definite Proportions -

no matter how a given chemical compound is prepared, it always contains the same elements in the same proportions by mass.

The Law of Multiple Proportions - 

if two elements combine to form more than one compound, the masses of one of the elements combining with a fixed mass of the other are in a simple ratio to one another

The Laws of Definite Proportions and Multiple Proportions and the related portions of atomic theory form the bases for most quantitative calculations involving chemical reactions.

Regardless of the type of bond (ionic, covalent, or metallic), specific amounts of one element will react with specific amounts of the element(s) with which it

is combined.

If two substances are placed together in a container, in any ratio, the result is a mixture.

The solvent is the material that dissolves the other substance(s).

Solubility is defined as the maximum amount of a substance that can dissolve in a given amount of solvent at a specific temperature.

The substances that dissolve in the solution are called solutes

.

A homogeneous mixture of two or more substances is called a solution

Equilibrium is the point at which the rates of the forward and reverse reactions are exactly equal for a chemical reaction if the conditions of reaction are constant.

Le Chatelier's Principle states that if a stress (for example, heat, pressure, concentration of one reactant) is applied to an equilibrium, the system will

adjust, if possible, to minimize the effect of the stress.

The term ppm is defined as the concentration of a solution in units of one part of solute to one million parts solvent.

Density is the measure of the mass per unit volume of a material

;

(density = mass/volume).

;

Molarity is defined as moles of solute per liter of solution.

;

Molarity (M) = moles of solute (n)/liters of solution (V)

;

Normality (N) is defined as the number of equivalents of solute dissolved in one liter of solution.

;

Acids are substances that dissociate in water to produce hydrogen (H+).

;

When an acid reacts with a base, forms two products: water and a salt.

;

A salt is an ionic compound composed of positive ions and negative ions

;

.

;

The

pOH of a solution is defined as the negative logarithm of the hydroxyl concentration, represented as [OH-

] in moles/liter.

Certain soluble salts (principally sodium, potassium, magnesium, and calcium) that have the property of combining with acids to form neutral salts are called

alkalies.

Bases are substances that produce hydroxide ions (OH

-

) in water solutions.

ph is defined as the negative logarithm of the hydrogen concentration, represented as [H +] in moles/liter.