Semester 1 Terminology

Question 1

Chemistry

Answer 1

The science that deals with the composition and properties of substances

Question 2

Quantity

Answer 2

A property that can be measured and described by a number and unit.

Question 3

SI System

Answer 3

The Standard International system for measurements, assures that scientists are using the same units when describing a quantity.

Question 4

Scientific Notation

Answer 4

Expressing numbers by powers of ten

Question 5

Significant Figures

Answer 5

The number of digits displayed for a calculated number, based on the number of digits used in the original information that is given or measured.

Question 6

Assumption

Answer 6

A conclusion that may or may not be correct, usually a combination of personal belief and partial bits of evidence.

Question 7

Atom

Answer 7

The smallest unit of matter

Question 8

Element

Answer 8

A single type of atom, of which there are over 100 different types, based on the number of protons in the nucleus.

Question 9

Compound

Answer 9

Chemically joined combinations of two or more atoms.

Question 10

Pure Substance

Answer 10

Composed of the same substance throughout, even on the submicroscopic scale. Includes elements and chemically joined combinations of elements, compounds.

Question 11

Mixture

Answer 11

Physically composed of many different substances; may appear to be a pure substance if mixed evenly, homogenous, or may be unevenly mixed, heterogeneous.

Question 12

Law of definite composition of compounds.

Answer 12

Compounds are pure substances, that are made up of a definite ratio, or definite composition, of chemically joined elements.

Question 13

Law of Multiple Proportions

Answer 13

The same elements that make one compound, can be joined together to make another completely different compound.

Question 14

Molecular Compounds

Answer 14

Function as independent particles; a compound where the ration of elements states how many of each element are actually in each independent molecule.

Question 15

Ionic Compounds

Answer 15

Function as a crystal lattice of particles; a compound where the ratio of elements states only the lowest common ratio, or the smallest crystal lattice of articles possible.

Question 16

Formula Unit

Answer 16

Smallest unit of an ionic compound’s network or crystal lattice.

Question 17

Ion

Answer 17

An element or compound with a charge. Due to loss or gain of electrons.

Question 18

Cation

Answer 18

Positive (+) ion due to loss of electrons

Question 19

Anion

Answer 19

Negative (-) ion due to gain of e

Question 20

Polyatomic Ions

Answer 20

Ions composed of many elements; a combination of elements with a charge.

Question 21

Alloy

Answer 21

A mixture of two or more metals.

Question 22

Chemical Reaction

Answer 22

When pure substances chemically combine or break apart to form new pure substances.

Question 23

Energy

Answer 23

The ability to do work or give off heat.

Question 24

Law of Conservation of Mass

Answer 24

In a closed or isolated system, matter cannot be created or destroyed. It can change forms but is conserved.

Question 25

Kinetic Energy

Answer 25

Movement, or work, related energy

Question 26

Potential Energy

Answer 26

Stored Energy

Question 27

Law of Conservation of Energy

Answer 27

Energy can neither be created nor destroyed - only converted from one form of energy to another.

Question 28

System

Answer 28

The set of substances and energy that is being studied

Question 29

Surroundings

Answer 29

What is in contact with the system.

Question 30

Exothermic

Answer 30

Heat leaves the system

Question 31

Endothermic

Answer 31

heat enters the system

Question 32

Combustion

Answer 32

An exothermic reaction in which a substance combines with oxygen to form products in which all elements are combined with oxygen. (Usually contains Carbon and Hydrogen and produce CO2 and H2O)

Question 33

Composition and Decomposition

Answer 33

Reactions that are putting together or taking apart a substance.

Question 34

Single Replacement Reactions

Answer 34

A metal replaces a metal or hydrogen in a compound, or a nonmetal replaces a nonmetal in a compound, based on their activity levels.

Question 35

Double Replacement Reactions

Answer 35

involves the switching of cations and anions for two aqueous compounds. AB + CD -> AD +CB

Question 36

Ionic Equation

Answer 36

a chemical equation where soluble compounds are shown as ions

Question 37

Net ionic Equation

Answer 37

Ions that appear on both sides of the ionic equation are not shown

Question 38

Avogadro's Number

Answer 38

6.022 × 10²³ The number of atoms in 12 grams of carbon 12

Question 39

Mole

Answer 39

Avogadro's number, usually in reference to atoms, molecules or particles which can be converted from grams to moles based on their respective atomic mass.

Question 40

Atomic Mass

Answer 40

The weighted average mass of the isotopes of an element.

Question 41

Molar Mass

Answer 41

The mass in grams of one mole of a pure substance

Question 42

Percent

Answer 42

Parts Per hundred

Question 43

Percent Composition (Percent mass)

Answer 43

How much of each component is in a mixture or compound.

Question 44

Empirical Formula

Answer 44

It is the lowest ratio of elements in a compound found from the experimental data.

Question 45

Molecular Formula

Answer 45

The actual formula of a compound; may be the same or multiple of the Empirical.

Question 46

Molarity

Answer 46

Concentration expressed in moles per Liter. Mol/L

Question 47

Stoichiometry

Answer 47

Derived from Greek - "to measure elements" Involves measuring or Calculating the amounts of elements or compounds involved in a chemical change.

Question 48

Limiting Reactant

Answer 48

The reactant that limits the amount of product that can be made.

Question 49

Excess reactant

Answer 49

The reactant that will still be left over when the limiting reactant is completely consumed.

Question 50

Theoretical Yield

Answer 50

Amount of product predicted based on balanced chemical equation.

Question 51

Actual Yield

Answer 51

The amount of product yielded in a reaction, according to real measurements.

Question 52

Percent Yield

Answer 52

The efficiency of a reaction described by the actual yield divided by the theoretical yield.

Question 53

STP

Answer 53

Standard temperature and pressure. Gases have approximately 22.4 L/mol at STP. Because the number of particles of a gas changes with both temperature and pressure a predetermined value for temperature and pressure is needed in order to make a useful conversion.