Fundamentals of Chemistry

Define “states of matter”

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

Define atomic weight

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

Define molecular weight

The weight of a molecule, the molecular weight

,

is the total mass of the individual atoms.

Define Mole

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.

Define gram atomic weight

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

Define gram molecular weight

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

 

LIST the components of an atom, relative sizes, and charges.

 

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STATE the criterion used to classify an atom chemically

 

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

 

DEFINE the following subdivisions of the periodic table:

 

– Periods

 

– Groups

 

– Classes

 

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Define Valence

 

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.

Define ionic bonds
An ionic bond is formed when one or more electrons is wholly transferred from one element to another, and the elements are held together by the force of attraction due to the opposing charges.
Define Van der Waals forces

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.

 

Define covalent bonding 

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.

Define metallic bonding

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

 

DESCRIBE the physical arrangement and bonding of a polar molecule.

 

When the shared pair of electrons is

NOT

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

 

DESCRIBE the three basic laws of chemical reactions.

 

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

 

STATE how elements combine to form chemical compounds.

 

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.

Define mixture

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

Define Solvent

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

Define solubility

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

Define Solute

The substances that dissolve in the solution are called solutes

.

Define Solution

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

Define equilibrium

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.

 

STATE Le Chateleir’s principle.

 

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.

Define Parts per Million (ppm)

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

Define density

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

;

(density = mass/volume).

Define molarity

;

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

;

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

;

Define normality

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

Define acid

;

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

;

Define salt

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

;

.

;

Define pOH

The

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

] in moles/liter.

Define Alkalies

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

alkalies.

Define Base

Bases are substances that produce hydroxide ions (OH

) in water solutions.

Define pH

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

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