Chapter 7: Chemical Quantities and Reactions

Mole

A group of atoms, molecules, or formula units that contains 6.02 x 10^23 of these items.

Avogadro’s Number

The number of items in a mole, is equal to 6.02 x 10^23.

Formula Unit

The groups of ions represented by the formula of an ionic compound.

Molar Mass

The quantity in grams that equals the atomic mass of an element.

Chemical Change

It occurs when a substance is converted into one or more new substances that have different formulas and different properties.

Chemical Reactions

These always involve chemical change because atoms of the reacting substances form new combinations with new properties.

Chemical Equation

It tells us the materials we need and the products that will form.

Balanced Equations

These show the same number of atoms for each element in the reactants as well as in the products.

Coefficients

The whole numbers in front of the formulas.

Law of Conservation of Matter

This States that matter cannot be created or destroyed during a chemical reaction.

Combination Reactions

Reaction from two or more elements or compounds bond that forms one product.

Decomposition Reactions

These occur when a reactant splits into two or simpler products.

Replacement Reactions

The element in a compound are replaced by other elements.

Single replacement reaction

A reacting element switches place with an element in the other reacting compound.

Double replacement reaction

The positive ions in the reacting compounds switch places.

Combustion Reactions

A carbon-containing compound, usually a fuel burns in oxygen from the air to produce carbon dioxide, water, and energy in the form of heat or flame.

Oxidation-Reduction Reactions

* **E**lectrons are transferred from one substance to another.
* If one substance loses electrons, another substance must gain electrons.

Oxidation

The loss of electrons.

Reduction

The gain of electrons.

cells of the body

In the ______, the oxidation of organic (carbon) compounds involves the transfer of hydrogen atoms, which are composed of electrons and protons.

biochemical oxidation–reduction

In _____ reactions, the transfer of hydrogen atoms is necessary for the production of energy in the cells.

Law of Conservation of Mass

States that there is no change in the total mass of the substances reacting in a chemical reaction.

mole–mole

The coefficients in an equation describing the relationship between the moles of any two components are used to write _____ factors.

Activation Energy

The amount of energy required to break the bonds between atoms of the reactants.

Collision

In this condition the reactants must collide

Orientation

In this condition the reactants must align properly to break and form bonds.

Energy

In this condition the collision must provide the energy of activation.

Heat of reaction

It is the difference between the energy of the reactants and the energy of the products.

Exothermic Reaction

The energy of the products is lower than the energy of the reactants.

Endothermic Reaction

The energy of the products is higher than that of the reactants.

Rate of Reaction

It is measured by the amount of reactant used up, or the amount of product formed, in a certain period of time.

Catalyst

It acts by providing an alternate pathway with a lower energy requirement.