Chemistry Midterm Review

105 terms by connorduncan

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Matter

anything that occupies space and has mass

Chemistry

the study of matter and the changes it undergoes

Substance

matter that has a definite composition and distinct properties

Mixture

a combination of two or more substances in which the substances retain their distinct identities

Homogeneous mixture

a mixture in which the composition with uniform composition (e.g. sugar dissolved in water)

Heterogeneous mixture

a mixture in which the composition is not uniform (e.g. oil and water)

Element

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

Compound

a substance composed of two or more elements chemically united in fixed portions (e.g. water)

Chemical property

a property that can only be observed when a chemical change is being carried out

Physical property

a property that can be measured and observed without changing the composition or identity of a substance

Extensive property

a property which is dependent on the quantity of matter that is being considered

Intensive property

a property which does not depend on the amount of matter being considered

Meter

SI unit for length

Kilogram

SI unit for mass

Second

SI unit for time

Kelvin

SI unit for temperature

Mole

SI unit for amount of substance/matter that contains as many atoms, molecules, or formula units as there are atoms in exactly 12g of carbon-12.

Mass

the measure of the quantity of matter in an object

Weight

the force that gravity exerts on an object

Liter

volume occupied by one cubic decimeter

Density

mass of an object divided by its volume

Accuracy

how close a measurement is to the true value of the quantity that was measured

Precision

how closely two or more measurements of the same quantity agree with one another

Law of Definite Proportions

law created by Proust which states that different samples of the same compound always contain its constituent elements in the same proportion by mass

Law of Multiple Proportions

law created by Dalton which states that the same two elements, when combined in different small whole-number proportions, make different compounds

Law of Conservation of Mass

law created by Lavoisier which states that matter can neither be created nor destroyed

Atom

the most basic unit of an element that can enter into a chemical combination

Radiation

the emission and trasmission of energy through space in the form of waves

Electrons

negatively charged particles

Radioactivity

the spontaneous emission of particles and/or radiation

Nucleus

dense central core area within an atom

Proton

positively charged particles in the nucleus

Neutron

electrically neutral particles with a slightly greater mass than protons

Atomic number

the number of protons in the nucleus of an atom of an element

Mass number

the total number of neutrons and protons present in the nucleus of an atom of an element

Periodic table

a chart in which elements having similar chemical and physical properties are grouped together

Period

a horizontal row in the periodic table

Group

a vertical column in the periodic table in which elements have similar chemical properties

Metal

an element that is a good conductor of heat and electricity

Nonmetal

an element that is a poor conductor of heat and electricity

Metalloid

an element that has properties intermediate to those of metals and nonmetals

Alkali metals

another name for Group 1A elements

Alkaline earth metals

another name for Group 2A elements

Halogens

another name for Group 7A elements

Noble gases

another name for group 8A elements

Molecule

an aggregate of at least two atoms in a definite arrangement held together by chemical forces

Ion

an atom or a group of atoms that has a net positive or negative charge

Cation

an ion with a net positive charge

Anion

an ion with a net negative charge

Molecular formula

a formula that shows the exact number of atoms of each element in the smallest unit of a substance

Empirical formula

a formula that shows the simplest whole-number ratios of the elements in a substance

Binary compounds

a compound formed from only two elements

Ternary compounds

a compound consisting of three elements

Acid

a substance that yields hydrogen ions when dissolved in water

Base

a substance that yields hydroxide ions when dissolved in water

Hydrates

compounds that have a specific number of water molecules attached to them

Atomic mass

mass of an atom in atomic mass units (amu)

Atomic mass unit

a mass exactly equal to 1/12 the mass of one carbon-12 atom

Avagadro's Number

6.02 x 10²³

Molar mass

the mass of one mole of atoms, molecules, or formula units

Molecular mass

the sum of the atomic masses in a molecule

Percent composition

percent mass of each element in a compound

Chemical reaction

a process in which a substance/substances is/are changed into one or more new substances

Chemical equation

an equation which uses chemical symbols to show what happens during a chemical reaction

Reactant

a starting material in a chemical reaction

Product

a substance formed as a result of a chemical reaction

Mole method

the interpretation of the coefficients in a chemical equation as the number of moles of each substance

Limiting reagent

the reactant used up first in a reaction

Excess reagent

a reactant present in quantities greater than necessary to react with the quantity of the limiting reagent

Solution

a homogeneous mixture of two or more substances

Solute

the substance in a solution that is present in a smaller amount

Solvent

the substance in a solution that is present in a larger amount

Aqueous solution

a solution in which the solute is initially a liquid or solid and the solute is water

Electrolyte

a substance that can conduct electricity when dissolved in water

Reversible reaction

a reaction which can occur in either direction

Chemical equilibrium

a chemical state in which no net change can be observed

Precipitation reaction

a reaction that results in the formation of a precipitate

Precipitate

an insoluble product that separates from a solution

Solubility

the maximum amount of solute that will dissolve in a given quantity of solvent at a given temperature

Molecular equation

an equation in which the formulas of the compounds are written as though they exist as molecules or whole units

Ionic equation

an equation in which dissolved species are shown as free ions

Spectator ions

ions that are not involved in the overall reaction

Net ionic equation

an equation in which only the species that actually take part in the reaction are shown

Oxidation state

the number of charges the atom would have in a molecule (or ionic compound) if electrons were transferred completely

Activity series

a convenient summary of the results of many possible displacement reactions

Concentration of a solution

the amount of solute present in a given quantity of solution

Molarity

a unit that measures the concentration of a solution and is defined as (moles of solute)/(liters of solution)

Pascal

one Newton per square meter

Atmospheric pressure

the pressure exerted by Earth's atmosphere

Standard atmospheric pressure

the pressure that supports a column of mercury exactly 760 mm high at 0°C at sea level (measured in atm)

Torr

a unit of pressure which is equal to 1 mmHg

10.13 kPa

the pressure, in kilopascals, that is equivalent to 1 atm of pressure

Absolute zero

theoretically the lowest attainable temperature

(P₁V₁/T₁) = (P₂V₂/T₂)

equation for combined gas law

PV = nRT

equation for ideal gas law

STP

The conditions of O°C and 1 atm

Ideal gas

a hypothetical gas whose pressure-volume-temperature behavior can be completely accounted for by the ideal gas equation

Law of Partial Pressures

law created by Dalton which states that the total pressure of a mixture of gases is the sum of the pressures that each gas would exert if it were present alone

Mole fraction

a dimensionless quantity that expresses the ratio of the number of moles of one component to the number of moles of all the components present

Joule

the SI unit of energy which is defined as 1 Newton-meter

Kinetic energy

the type of energy expended by moving an object

Kinetic Molecular Theory

a theory whose central assumptions are that
1. Molecules of a gas possess mass but have a negligible volume in relation to their distances from one another
2. Gas molecules are in constant motion and frequently experience elastic collisions
3. Gas molecules do not exert intermolecular forces on one another
4. Any two gases at the same temperature will have the same average kinetic energy

Diffusion

the gradual mixing of molecules of one gas with molecules of another by virtue of their kinetic properties

Graham's Law of Diffusion

law created by Graham which states that under the same conditions of temperature and pressure, rates of diffusion for gases are inversely proportional to the square roots of their molar masses

Effusion

the process by which a gas under pressure escapes from one compartment of a container to another by passing through a small opening

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