Pre-Chemistry

A
Accuracy

Accuracy

How close a measured value is to the accepted or real value.
Actual Yield

Actual Yield

The amount of products actually formed during a chemical reaction.
Ampere

Ampere

Electric current equal to one coulomb per second.
Angular Momentum Quantum Number

Angular Momentum Quantum Number (l)

The shape of an orbital.

0,1,2,3,…,n-1

Each value for l is a subshell

Each number value of l is assigned a letter s,p,d,f,g….

When:
n=1, l=0: 1s
n=2, l=0,1: 2s,2p
Anion (-)

Anion (-)

Elements that have unpredictable properties.

A main group NONMETAL will GAIN electrons to form an ANION with the same number of electrons as the nearest noble gas.
Aqueous Solution

Aqueous Solution

A solution where the solvent is water.
Arrhenius Acid

Arrhenius Acid

A substance that produces \(H^{+}\) in an aqueous solution, strong acids completely dissociate in aqueous solution
Arrhenius Base

Arrhenius Base

A substance in an aqueous solution that produces \()H^{-}\), strong bases completely dissociate in aqueous solution.
Atomic Mass

Atomic Mass

Is the weighted average of isotopic masses based on the natural abundance of each isotope.
Atomic Number

Atomic Number

The number of protons in the nucleus of an atom. The type of atom/element is determined by the number of protons.
Aufbau Principal

Aufbau Principal

Electrons occupy lower energy orbitals before filling higher energy orbitals.
C
Candela

Candela

A monochromatic radiation frequency of \(5.40x10^{13}\) Hz with a radiant intensity of \(\frac{1}{683}\) watt per steradian from a source in a given direction.
Charge

Charge

Electrons and protons have charge that is equal and opposite, because of this we can say the relative charge in atomic units is one.
Chemical Symbol

Chemical Symbol

A one or two letter abbreviation assigned to each element.
Core Electrons

Core Electrons

Electrons in a filled inner shell.
Cation (+)

Cation (+)

One or more atoms that has lost an electron(s).

A main group METAL will LOSE electrons to form a CATION with the same number of electrons as the nearest noble gas.
D
Density

Density

A ratio of mass (m) to volume (V) of a substance.
E
Electron

Electron

A negatively charged particle located in the volume of space surrounding the nucleus of an atom.
Electronic Configurations

Electronic Configurations

A notation that represents the orbitals occupied by electrons in an atom.

Write the value of n, followed by the number of electrons allowed in each orbital until all electrons in the atom are assigned to an orbital.

Example Carbon: 6 electrons = \(1s^{2}2s^{2}2p^{2}\)
Element

Element

One or more atoms of the same type.
Exact Number

Exact Number

A number with an unlimited amount of significant figures.
H
Hund’s Rule

Hund’s Rule

Electrons will singly occupy degenerate orbitals until they are half full before pairing up with other electrons. Electrons in half full orbitals will have the same spin.
Hydronium ion

Hydronium ion

The ion formed when a proton associates with water to form \(H_{3}O\).
Hydroxide

Hydroxide

The \(OH^{-}\) ion.
I
Insoluble

Insoluble

A substance that does not readily dissolve in water.
Ions

Ions

One or more atoms that has gained or lost an electron(s).

Ions are charged particles.

See also, Cation(+) and Anion(-)
Ion Notation

Ion Notation

Ions are represented as the chemical symbol of the ion with the charge of the ion noted as a superscript to the right.

\(\text{X}^{\text{charge}}\)

Lithium ion \(=\text{Li}^{\text{+}}\), Oxygen ion \(=\text{O}^{2-}\)
K
Kelvin

Kelvin

The absolute temperature scale, 0K is assigned to absolute zero, the temperature at which all molecular motion stops
Kilogram

Kilogram

The measurement the mass of an object, how much matter it contains. Defined by a metal cylinder housed at the International Bureau of Weights and Measures in Sevres France.
M
Magnetic Quantum Number \(m_{l}\)

Magnetic Quantum Number \(m_{l}\)

Orientation of orbital in 3D space.

Value= integer values from –l…l.

There are 2(l)+1 values of \(m_{l}\) for each value of l.

Examples:
When:
l=0, \(m_{l}\) = 0
l=1, \(m_{l}\) = -1,0,1
2(0)+1=1 value of \(m_{l}\)
2(1)+1=3 values \(m_{l}\)
Mass Number

Mass Number

The sum of the number of neutrons and protons in the nucleus of an atom.
Measurement

Measurement

A numeric quantity in which every digit, except the last, is certain. The last digit is estimated, leading to an uncertainty in the measurement.
Meter

Meter

The distance light travels through a vacuum in 1/299792458s
Mole

Mole

Is defined as \(6.022x10^{23}\) objects.
Molecular Compounds

Molecular Compounds

Two or more bonded atoms of different types.
Molecular Elements

Molecular Elements

Two or more bonded atoms of the same type.
Molecule

Molecule

Two or more bonded atoms.
N
Neutron

Neutron

A neutral particle located in the nucleus of an atom.
Nucleus

Nucleus

The small dense core of an atom consisting of neutrons and protons. Neutrons and protons have approximately the same mass.
O
Oxidant

Oxidant

Gains electrons, is the oxidizing agent.
Oxidation

Oxidation

The loss of electrons.
P
Pauli Exclusion Principle

Pauli Exclusion Principle

No two electrons in an atom can have the same four quantum numbers. But.. Any three quantum numbers can be the same.

This implies: One orbital may contain two electrons of opposite spin orientation!

Single electron atom

Multi-electron atom
Percent Yield

Percent Yield

Actual products formed as a percentage of the theoretical yield.
\(\text{Percent Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} x 100\)
Precision

Precision

The degree of reproducibility of a measured quantity; how close a series of measurements of the same quantity are to one other.
Principle Quantum Number (n)

Principle Quantum Number (n)

Orbital’s size and energy level of an electron.

A whole number 1,2,3,4…..

n increases with an electron’s energy and distance from the nucleus.

Each level is called a shell.
Products

Products

Materials produced in a chemical reaction
\(2H_{2} + 0_{2}\) \(\to 2H_{2}O\)
Proton

Proton

A positively charged particle located in the nucleus of an atom.
Pure Substance

Pure Substance

Two or more molecules or atoms of the same type.
R
Reactants

Reactants

Materials consumed in a chemical reaction.
\(2H_{2} + 0_{2}\) \(\to 2H_{2}O\)
Reaction Equation

Reaction Equation

The notation used to illustrate a chemical reaction.
\(2H_{2} + 0_{2} \to 2H_{2}O\)
Reductant

Reductant

Loses electrons is the reducing agent.
Reduction

Reduction

The gain of electrons.
S
Second

Second

The duration of 9,192,631,770 periods of the radiation emitted from a transition in a cesium-133 atom.
Significant Figures

Significant Figures

The number of non-place holding digits in a reported measurement. A larger amount of significant figures means a larger precision in the measurement.
Solubility

Solubility

The maximum amount of solute that can dissolve in a solvent at a given temperature.
Soluble

Soluble

A substance that readily dissolves in water to a significant extent.
Solute

Solute

Material present in a solution that has a smaller molar amount.
Solution

Solution

A homogenous mixture of two or more substances consisting of ions or molecules.
Solvent

Solvent

Material present in a solution that has the larger molar amount.
Spin Quantum Number \(m_{s}\)

Spin Quantum Number \(m_{s}\)

Spin is intrinsic to all electrons, it is quantized, with only two orientations; spin up or spin down.

Value \(=+\frac{1}{2}\) OR \(-\frac{1}{2}\)
States of Matter Notation

States of Matter Notation

The state that each of the products and reactants are in during the reaction; (s)-solid, (l)-liquid, (g)-gas, (aq)-aqueous.
\(2H_{2(g)} + 0_{2(g)} \to 2H_{2}O_{(g)}\)
T
Theoretical Yield

Theoretical Yield

The amount of products formed in a chemical reaction based on stoichiometric calculations.
V
Valence Electrons

Valence Electrons

Electrons in the outermost shell (highest n value).

Example Carbon:
6 electrons = \(\stackrel{1s^{2}}{Core}\) \(\stackrel{2s^{2}2p^{2}}{Valence}\)
Volume

Volume

A unit of length raised to the third power, volume is a measure of space.

Glossary

Glossary of Terms

A

C

D

E

H

I

K

M

N

O

P

R

S

T

V