Chemistry Midterm Vocab

Acid Base reaction

(also called neutralization reactions) generally form water and an ionic compound—called a salt—that usually remains dissolved in the solution.

Aqueous Solution

a substance is dissolved in water. When a substance dissolves in water, the mixture is called a solution.

Balanced Equation

represents a chemical reaction.

Combustion Reaction

Combustion reactions are a subcategory of oxidation–reduction reactions, in which electrons are transferred from one substance to another.

Complete ionic equation

show aqueous ionic compounds that normally dissociate in solution as they are actually present in solution.

Decomposition reaction

a complex substance decomposes to form simpler substances.

Double displacement reaction

two elements or groups of

elements in two different compounds exchange places to form two new compounds. can be precipitation reactions, acid–base reactions, and gas evolution reactions.

gas-evolution reaction

Reactions that occur in liquids and form a gas

insoluble

Does not dissolve in the liquid

molecular equation

a chemical equation showing the complete, neutral formulas for every compound in a reaction.

net ionic equation

whihc show only the species that actually participate in the reaction

neutralization reaction

Form water adn an ionic compound

oxidization-reduction (redox) reaction

Reactions involving the transfer of electrons

precipiate

The solid which forms after the two aqueous solutions are mixed.

precipiation reaction

when two aqueous solutions react and a solid is formed.

salt

ionic compound form in acid based reactions.

Single displacement reaction

one element displaces another in a compound.

solubility rules

soluble

dissolves in that specific liquid

spectator ions

some of the ions in solution appear unchanged on both sides of the equation. These ions are called spectator ions because they do not participate in the reaction.

strong electrolyte solution

Substances (such as NaCl) that completely dissociate into ions in solution are called strong electrolytes.

synthesis (combination) Reaction

two simple substances combine to make a more complex substance.

Matter

Anything that occupies space and has mass and is made up of atoms. Ex. Water, Wood, Steel

atoms

submicroscopic particles that are fundamental building blocks of matter

molecules

2 or more atoms joined together in specific geometrical arrangements

Crystalline

Atoms or molecules arrange in geometric patterns with long range repeating order Ex. Salt and Diamond

amorphous

atoms or molecules do not have a long range order.

Liquid Matter

Free to move relative to one another
Molecules: Close together
Shape: Indefinite
Volume: Definite
Compressablity: Incompressible

Gaseous Matter

Free to move relative to one another
Molecules: Far apart
Shape: Indefinite
Volume: Indefinite
Compressablity: Compressible

Solid Matter

Oscillation/ vibration about fixed point
Molecules: Close together
Shape: Definite
Volume: Definite
Compressablity: Incompressible

Pure Substance

composed of only one kind of atoms or molecules

Mixtures

Composed of two or more kinds of atoms or molecules combined in variable proportions.

Element

A substance that cannot be broken down into simpler substaces

Compound

A pure substance Composed of two or more elements in fixed definite proportions

Heterogenous Mixture

A mixture in which the composition is not uniform throughout

Homogenous Mixture

A mixture in which the composition is uniform throughout

Physical Property

Is one that a substance displays wtithout changing its composition

Chemical Property

Is one that a substance displays only through changing its composition

Physical Change

Matter changes its appearance but not its composition

Chemical Change

Matter does not change its composition

Reactants

the substances present before the chemical change

Products

The substances present after the chemical change

Law of Conservation of Mass

matter is neither created nor destroyed in an ordinary chemical reaction.

Chemical Reaction

the sum of the masses of the reactants will be equal to the sum of the masses of the products

Energy

Capacity to do work

The Law of Conservation of Energy

The law of conservation of energy states that energy is neither created nor destroyed, the total amount of energy is constant, and energy can be changed from one form to another.

Work

defined as the result of a force acting through a distance

Electrical Energy

Associated with the flow of electrical charge

Thermal Energy

associated with the random motions of atoms and molecules in matter

Chemical Energy

form of potential energy associated with the positions of the particles that compose the chemical system.

1 cal

4.184 joules

1 Cal

1000 calories

1 kWh

3.60 × 10 ^ 6 Joules

TNT Molecules

tend to go through rapid chemical changes that lower their potential energy making them explosive.

Exothermic

Energy is Released

Temperature of a substance

is a measure of the thermal energy of matter

Heat

which has units of energy, is the transfer or exchange of thermal energy caused by a temperature difference.

On the Farenheit Scale

Water freezes at 32 ºF.
Water boils at 212 ºF.
Room temperature is approximately 72 ºF.

On the Celcius Scale

Water freezes at 0 ºC.
Water boils at 100 ºC.
Room Temperature isapproximately 22 ºC.

Kelvin Scale

avoids negative temperatures
by assigning 0 K to the coldest temperature possible,
absolute zero.
Absolute zero is the temperature at which molecular
motion virtually stops.
Water freezes at 273 K.
Water boils at 373 K.
Room temperature is approximately 295 K.

K

C + 273.15

C

F - 32 / 1.8

Specific Heat Capacity

is the quantity of heat (usually in joules) required to change the temperature of 1 g of the substance by 1 C.
J / g C

C

specific Heat Capacity

ΔT

Temerature change =
Tf-Ti

Kinetic Energy

the energy associated with its
motion

Potential Energy

the energy
associated with its position or composition.

States of Matter

Liquid, Gas, Solid

Can energy be transferred between objects?

Yes

Can energy be created out of nothing or vanish into nothing

NO

Endothermic Reaction

Energy is Absorbed

Q

Heat

M

mass in grams

Leucippus and Democritus

theorized that matter was ultimately composed of small, indivisible particles. Democritus suggested that if you divided matter into smaller and smaller pieces, you would eventually end up with tiny, indestructible particles called atoms.

John Dalton

Each element is composed of tiny indestructible particles called atoms. All atoms of a given element have the same mass and other properties that distinguish them from the atoms of other elements. Atoms combine in simpler, whole number ratios to form compounds.

J. J Thompson

Discovered the electron and that they are negatively charged, that they are much smaller and lighter than atoms. His experiments proved that the indestructible atom can be chipped. Raised the question of balancing positive charge. At that time atoms were known as having neutral charge. Plum Pudding Model suggested negatively charged electron are held in a sphere of positive charge.

Ernest Rutherford

Tried to prove J.J Thompson model right but proved it wrong. Directed tiny, positively charged particles called alpha particles at an ultrathin sheet of gold foil. Alpha particles are about 7000 times more massive than electrons and carry a positive charge. These particles act like probes of the gold atoms structure. The results showed that most particles passed through but some deflected and some bounced back.

Nuclear Theory of the atom

Most of the atom’s mass and all of its positive charge are contained in a small core called the nucleus. Most of the volume of the atom is empty space through which the tiny negatively charged electrons are dispersed. There are many charged electrons outside the nucleus as there are positively charged particles indie the nucleus, so that the atoms is electrically neutral.

Electrical charge

fundamental property of protons and electrons just as mass is a fundamental property of matter. Positive and negative electrical charges attract each other. Positive and positive and negative and negative charges repel each other. Positive and negative charges cancel each other when paired the charge is neutral.

Atomic Number

the number of protons in the nucleus

Periodic law

When the elements are arranged in order of increasing relative mass, certain sets of properties recur periodically. Mendeleev organised all the known elements in a table in which relative mass increased from left to right and elements with similar properties were aligned in the same vertical columns. Mendeleev left gaps for elements that weren’t discovered yet.

Periodic Table

elements are listed in increasing atomic number and mass

German chemist Clemens Winkler

discovered element called eka-silicon

Metals

occupy the left side of the periodic table and have similar properties: they are good conductord of electricity and heat. Malleable, ductile, often chiny and they tend to lose electrons when they go through chemical changes.

Non metals

occupy the right side of the periodic table and poor conductors of heat and electricity and they gain electrons when they go through chemical changes.

metalloids

semi conductos because of their intermediate electrical conductivity can be changed or controlled.

Noble Gases

chemically inert gases

Alkali metals

very reactive metals

Alkaliine Metlas

fairly reactive

halogens

very reactive non-metals

ions

atoms often lose or gain electrons that create charged particales.

ion charge formula

ion charge = # protons - # electrons

cations

postively charged ions

anions

negatively charged ions

valence electrons

outermost electrons in an atom

Isotopes

atoms with thename number of protons ut different numbers of neutrons. Writing: A / z X or X - A

atomic number (z) mass number (A) chemical symbol (X) and #n = Z - A

Percent natural abudance

percents in isotopes

mass number (A)

number of protons + number of neutrons

Atomic Mass

Percent tunred into decimal times number + percent turned into decimal times number = # amu

chemical formula

indicates the elements present in the compound and the relative number of atoms of each element.