CHEM FINAL VOCAB

natural science

branches of knowledge and study which deal directly with natural objects.

natural science

include chemistry, physics, biology, geology, and astronomy.

physics

the fundamental science

biology

the life science

chemistry

the central science

chemistry

the study of matter and the changes that it may undergo

chemistry

the science that seeks to understand the properties of matter by studying the structure of the particles that compose it

matter

anything that has mass and takes up space

mass

a measure of the amount of material in an object

weight

the force that a mass experiences under the pull of gravity

chemical change

a substance is transformed into a chemically different substance. A chemical change is usually called a chemical reaction.

physical change

a change in which a substance changes its physical appearance but not its composition.

chemical property

properties which describe the way a substance may change or react to form other substances. ex: flammability

physical property

properties of a substance which can be measured without changing the identity and composition of the substance. ex: color, odor

density

mass per unit volume

intensive property

a property of a system which does not depend on how much of the system is present

extensive property

a property of a system which does depend on how much of the system is present

homogenous

uniform throughout

heterogenous

not uniform throughout

solid

state of matter with a definite shape and a definite volume

liquid

state of matter with a definite volume, but no specific shape

gas

state of matter with no definite shape or volume

element

a substance which cannot be separated into simpler substances by chemical means

atom

submicroscopic particle that constitutes the fundamental building block of ordinary matter

compound

a substance composed of two or more elements united chemically indefinite proportions

molecule

two or more atoms joined chemically in a specific geometrical arrangement

molecule

a covalently bonded compound

mixture

a substance composed of two or more particles in proportions that can vary from one sample to another

isotopes

atoms of the same element with different numbers of neutrons

ion

a charged particle

`cation

a positively charged ion

anion

a negatively charged ion

energy

the capacity to do work or to transfer heat

kinetic energy

energy of motion

potential energy

stored energy that results from the attractions and repulsions an object experiences in relation to other objects.

temperature

a measure of the average kinetic energy of the particles that make up a substance.

heat

energy of the random motion of the particles that make up a substance

work

energy used to cause an object to move against a force

work

energy of ordered motion

first law of thermodynamics

law of conservation of energy

first law of thermodynamics

energy is neither created nor destroyed, simply converted from one form to another

first law of thermodynamics

▵E = q + w

Law of Conservation of Mass

In a chemical reaction, matter is neither created nor destroyed

Antoine Lavoisier

formulated the Law of Conservation of Mass in 1789

Law of Definite Proportions

All samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constituent elements

Joseph Proust

formulated the Law of Definite Proportions in 1792

Law of Multiple Proportions

When two elements (call them A and B) form two different compounds, the masses of element B that combine with 1 gram of element A can be expressed as a ratio of small whole numbers

John Dalton

published the Law of Multiple Proportions in 1804

solution

a homogeneous mixture

thermochemistry

the study of the relationships between chemistry and energy

chemical energy

the energy associated with the relative positions of electrons and nuclei in atoms and molecules

thermal energy

the energy associated with the temperature of an object

system

the part of the universe whose properties one wishes to study

surroundings

all other parts of the universe besides the system, whose properties are not of immediate interest

endothermic process

a process in which the system gains heat from the surroundings

exothermic process

a process in which the system loses heat from the surroundings

intensive property

a property that is independent of the amount of the substance

intensive property

temperature, pressure, density

extensive property

a property that depends on the amount of a substance

extensive property

mass, volume, moles

first law of thermodynamics

the energy of the universe is constant

internal energy

the sum of the kinetic and potential energies of all of the particles that compose a system

state property

property of a system that defines the current state of a system

heat capacity

an extensive property of a system which tells how much energy is required to effect a change of the system in temperature of one Kelvin

specific heat

an intensive property of a system which tells how much energy is required to raise the temperature of
one gram of the system by one Kelvin

specific heat

heat capacity / mass

calorimetry

the process of measuring the amount of heat released or absorbed during a chemical reaction

enthalpy

a state function of a system defined to be the sum of the internal energy and the product of the pressure and volume of the system

Hess's Law

if a chemical equation can be expressed as the sum of a series of steps, then the enthalpy of reaction for the overall equation is the sum of the heats of reactions for each step

entropy

a thermodynamic state function representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system

entropy

a thermodynamic state function that increases with the number of energetically equivalent ways to arrange the components of a system to achieve a particular state

spontaneous process

a process that occurs without ongoing outside
intervention.

Second Law of Thermodynamics

the entropy will increase for any spontaneous
process in an isolated system

Second Law of Thermodynamics

the entropy of the universe will increase for any spontaneous process

reversible process

a process that reverses direction upon an infinitesimally small change in some property

Gibb's free energy

a criterion for spontaneity like the entropy of the universe, but one that focuses entirely on the system

Third Law of Thermodynamics

the entropy of a perfect crystal at absolute zero
(0 K) is zero.

science

An organized way of gathering and analyzing evidence about the natural world

solvent

the majority component of a solution

mole

A unit defined as the amount of material containing 6.0221421x10^23 particles.

degenerate

describes two or more electron orbitals with the same value of n that have the same energy

solute

A substance that is dissolved in a solution

solute

the minority component in a solution

allotropes

different physical forms of the same element in the same physical state

valence electrons

The electrons that are important in chemical bondingv

valence electrons

electrons that are present in the outermost principal energy level.

electrolytes

substances that dissolve in water to form solutions that conduct electricity

coordinate covalent bond

the bond formed when a ligand donates electrons to an empty orbital of a metal in a complex ion

coordinate covalent bond

dative bond

solubility

The amount of a substance that will dissolve in a given amount of solvent

covalent bond

A chemical bond in which two atoms share electrons that interact with the nuclei of both atoms, lowering the potential energy of each through electrostatic interactions

ionic bond

A chemical bond formed between two oppositely charged ions, generally a metallic cation and a nonmetallic anion,, that are attracted to one another by electrostatic forces

electronegativity

The ability of an atom to attract electrons to itself in a covalent bond

polar bond

A covalent bond between two atoms with significantly different electronegativities, resulting in the uneven distribution of electron density

nonpolar bond

A type of chemical bond that is formed when electrons are shared equally between two atoms

dipole moment

A measure of the separation of positive and negative charge in a molecule

diffraction

The phenomena by which a wave emerging from an aperture spreads out to form a new wave

electromagnetic radiation

A form of energy embodied in oscillating electric and magnetic fields

photon

The smallest possible packet of electromagnetic radiation with an energy equal to hv

frequency

For waves, the number of cycles that pass through a stationary point in one second