Chemistry Semester 1 Final Exam

Chapter 1

hypothesis

A proposed explanation for an observation or scientific problem, which can be tested by further investigation.

mass

A measure of the quantity of matter in an object.

property

A characteristic or quality of a substance.

matter

Anything that has substance and takes up space; anything that has mass and volume.

volume

The amount of space a sample of matter occupies.

meniscus

The curvature of the top of a liquid in a container, which is the result of intermolecular attractions between the liquid and the container.

water displacement

A method for measuring the volume of a solid object by immersing it in water. The volume of the object is equal to the amount of water displaced by the object when fully submerged.

density

The measure of the mass of a substance per unit of volume, often expressed as grams per milliliter, g/mL, or grams per cubic centimeter, g/cm^3.

intensive property

A characteristic, such as boiling point or density, that does not depend on the size of amount of matter and can be used to identify matter.

extensive property

A characteristic, such as volume or mass, that is specific to the amount of matter and therefore changes if the quantity of the substance changes.

density formula

D=M/V

Chapter 2

element

A unique substance that cannot be broken down into simpler substances through physical or chemical processes. Elements serve as the building blocks of matter.

compound

A pure substance that is a chemical combination of two or more elements in a specific ratio.

chemical formula

A combination of element symbols and numbers representing the composition of a chemical compound.

phase/state symbols

Th e physical form of matter such as the solid (s), liquid (l). or gaseous state (g).

aqueous

A solution in which water is the dissolving medium or solvent.

chemical change/reaction

A transformation that alters the composition of one or more substances such that one or more new substances with new properties are produced.

physical change

A change that alters the form of a substance but does not change the chemical identity of a substance.

reactivity

The tendency of an element or compound to combine chemically with other substances, as well as the ease or speed of the reaction.

atomic mass

The mass of a single atom (or isotope) of an element.

atomic number

The consecutive whole numbers associated with the elements on the periodic table. Th e atomic number is equal to the number of protons in the atomic nucleus of an element.

group

A vertical column on the periodic table, also called a family. Elements in a group have similar properties.

alkali metal

The elements in Group 1A on the periodic table, except for hydrogen.

alkaline earth metal

The elements in Group 2A on the periodic table.

halogens

The elements in Group 7A on the periodic table.

noble gas

The elements in Group 8A on the periodic table. Noble gases are known for not being reactive.

period

The elements in a horizontal row on the periodic table.

main group elements

The elements in Groups 1A to 7A on the periodic table.

transition elements

The elements in Groups 1B to 8B on the periodic table.

lanthanides

A series of elements that follow lanthanum in Period 6 of the periodic table; they are typically placed separately at the bottom of the periodic table.

actinides

A series of elements that follow actinium in Period 7 of the periodic table and that are typically placed separately at the bottom of the periodic table.

metal

An element that is generally shiny and malleable and an excellent conductor of heat and electricity. Metals are located to the left of the stairstep line on the periodic table.

nonmetal

An element that does not exhibit metallic properties. Nonmetals are often gases or brittle solids at room temperature. Nonmetals are poor conductors of heat and electricity and are located to the right of the stair-step line on the periodic table.

metalloid

An element that has properties of both metals and nonmetals. Metalloids are located along the stair-step line of the periodic table.

law of conservation of mass

The scientific law that states that mass cannot be gained or lost in a chemical reaction and that matter cannot be created or destroyed.

Chapter 3

model

A simplified representation of a real object or process that facilitates understanding or explanation of that object or process.

atom

The smallest unit of an element that retains the chemical properties of that element and can exist as a separate particle.

atomic theory

A theory that states that all matter is made up of individual particles called atoms.

nucleus

The dense, positively charged structure composed of protons and neutrons that is found in the center of an atom.

proton

A positively charged particle located in the nucleus of an atom. Th e mass of a proton is almost exactly equal to that of a neutron, about 1 amu.

neutron

A particle that is located in the nucleus of an atom and does not have an electric charge. Th e mass of a neutron is almost exactly equal to that of a proton, about 1 amu.

electron

An elementary particle with a negative charge that is located outside of the nucleus of an atom. It has a mass of about 1/1838 amu.

isotope

Atoms of the same element that have different numbers of neutrons. These atoms have the same atomic number but diff erent mass numbers.

mass number

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

radioactive

Any isotope that has an unstable nucleus and decays over time.

half-life

The amount of time required for one-half of the radioactive atoms in a sample to decay.

nuclear reaction

A process that changes the energy, composition, or structure of an atom's nucleus.

alpha decay

A nuclear reaction in which an atom emits an alpha particle consisting of two protons and two neutrons. Alpha decay decreases the atomic number of an atom by 2 and the mass number by 4.

beta decay

A nuclear reaction in which a neutron changes into a proton and an electron, and the atom emits a beta particle, which is the electron. Beta decay increases the atomic number of the atom without changing the mass.

beta particle

An electron emitted from the nucleus of an atom during beta decay.

alpha particle

A particle made of two protons and two neutrons, equivalent to the nucleus of a helium atom.

gamma ray

Electromagnetic radiation with the shortest wavelengths, less than 10 211 m. Emitted when a nucleus decays or during a nuclear explosion. Used in irradiation of food and in some cancer treatments.

fission

The splitting apart of an atomic nucleus into two smaller nuclei, accompanied by a release of energy.

fusion

The joining of two atomic nuclei to form a larger nucleus, accompanied by a release of energy.

nuclear equation

A representation of a nuclear reaction written with isotope symbols.

parent isotope

A radioactive isotope that undergoes decay.

daughter isotope

An isotope that is formed as a result of a nuclear reaction.

Chapter 4

valence electron

The electrons located in the outermost electron shell of an atom, which participate in chemical bonding.

valence shell

The outermost electron shell in an atom.

core electron

All electrons in an atom that are not valence electrons.

electron configuration

A notation for keeping track of where the electrons in an atom are distributed among the shells and subshells in an atom.

electromagnetic radiation

A large range of waves, some visible, some invisible, all traveling at the speed of light, in a vacuum, and at widely varying wavelengths and frequencies.

wavelength

The distance between two peaks or two troughs of a wave, usually measured in meters. Th e symbol for wavelength is l (lambda).

frequency

The number of waves that pass by a certain point in space per second, abbreviated as f. Th e frequency of light is measured in hertz, Hz.

ion

An atom or group of bonded atoms that has a positive or negative charge.

cation

An ion that has a positive charge.

anion

An ion that has a negative charge.

ionic compound

A compound that consists of positively charged metal cations and negatively charged nonmetal anions formed when valence electrons are transferred.

rule of zero charge

Th e rule that states that in an ionic compound, the positive charges on the metal cations and the negative charges on the nonmetal anions add up to zero.

polyatomic ion

An ion that consists of two or more atoms covalently bonded.

Chapter 5

soluble

Capable of being dissolved into another substance.

insoluble

Unable to be dissolved in another substance.

conductivity

A property that describes how well a substance transmits electricity, heat, or sound.

chemical bond

An attraction between atoms that holds them together.

ionic bond

A type of chemical bonding that is the result of the transfer of electrons from one atom to another, typically between metal and nonmetal atoms.

molecular covalent bond

A type of chemical bonding characterized by the sharing of valence electrons between atoms, resulting in individual units called molecules.

metallic bond

A type of bonding between metal atoms in which the valence electrons are free to move throughout the substance.

network covalent bond

A type of chemical bonding characterized by the sharing of valence electrons throughout the entire solid sample.

molecule

A group of atoms that are covalently bonded together.

Chapter 6

molecular formula

The chemical formula of a molecular substance, showing the identity of the atoms in each molecule and the ratios of those atoms to one another.

structural formula

A two-dimensional drawing or diagram that shows how the atoms in a molecule are connected. Each line represents a covalent bond.

isomer

Compounds with the same molecular formula but diff erent structural formulas. Isomers diff er in molecular structure and in chemical and physical properties.

HONC 1234

A rule that states that in most molecules, hydrogen makes 1 bond, oxygen makes 2 bonds, nitrogen makes 3 bonds, and carbon makes 4 bonds.

lewis dot structure

A diagram that shows a molecule's structure by using dots to represent the valence electrons.

lewis dot symbol

A diagram that uses dots to represent the valence electrons of a single atom.

bonded pair of electrons

A pair of electrons that are shared in a covalent bond between two atoms.

lone pair of electrons

A pair of unshared valence electrons that are not involved in bonding in a molecule.

octet rule

Nonmetal atoms combine by sharing electrons so that each atom has a total of eight valence electrons. Aft er bonding, each atom resembles a noble gas in its electron arrangements.

single bond

A covalent bond where two electrons are shared between two atoms.

double bond

A covalent bond where four electrons are shared between two atoms.

triple bond

A covalent bond in which three electron pairs are shared between two atoms.

functional group

A structural feature of a molecule; consists of a specific arrangement of atoms, responsible for certain properties of the compound.

synthesis

The creation of specific compounds by chemists, through controlled chemical reactions.

chemical equation

A representation of a chemical reaction written with chemical symbols and formulas.