General Chemistry placement test Study Guide

physical/phase change

(s)-->(l)-->(g), diluting, crush, cut. Still same substance.

Ethyl Group

-C2H5

Methyl Group

-CH3

Metallic Bonds

A "sea of mobile electrons" surrounding positive metal ions Ex: metal to metal Cu-Cu-Cu-Cu

Mixture

A PHYSICAL blend of two or more components

physical property

A characteristic of a substance that does not involve a chemical change. Ex. melting/boiling point, solubility, density, color, or hardness.

Exothermic reaction

A chemical reaction that RELEASES energy as a product Negative delta H (heat of reaction) "hot to touch"

liquid

A form of matter that flows, has constant volume, and takes the shape of its container

empirical formula

A formula showing the lowest whole number ratio of atoms in a compound. Can't be reduced.

Alkene

A hydrocarbon that contains a double bond.

heterogeneous mixture

A mixture in which different materials can be seen easily. Ex. soil, chocolate chip cookies

homogeneous mixture

A mixture that is so evenly mixed that you can't see all of the different parts. Ex. Air, kool-aid

Bohr Model

A model resembling planets revolving around the sun in orbits, useful in visualizing the structure of atoms.

Density

A physical property. Specific to every element.

Compound

A pure substance made of two or more elements CHEMICALLY combined.

Endothermic reaction

A reaction that ABSORBS energy in the form of heat. Positive delta H (heat of reaction) "cold to touch"

Nucleus

A region that is located at the center of an atom and contains most of the atom's mass (protons and neutrons)

solid

A state of matter that has a definite shape and a definite volume

gas

A state of matter with no definite shape or volume

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom. Mass = 1 amu

Element

A substance that cannot be broken down into simpler substances

Electron

A tiny, negatively charged particle that moves around the nucleus of an atom.

Saturated hydrocarbon

All of the bonds are single bonds

Anion

An atom that gained electrons and therefore has a negative charge. Nonmetals gain electrons

Cation

An atom that lost electrons and therefore has a positive charge. Metals lose electrons

Matter

Anything that has mass and takes up space

Ions

Atom or group of atoms(polyatomic) with a positive or negative electrical charge due to a loss or gain of electrons. Ex: Na+, Cl- , NO3-

Electronegativity (EN)

Atom's ability to attract and hold electrons.

Isotopes

Atoms of the same element having different masses because they contain different numbers of neutrons.

Writing Covalent/Molecular Substances

Both nonmetals use prefixes to tell # of atoms of each element. (mono, di, tri, tetra)

Compound

Can be decomposed by chemically

Groups of Periodic Table

Columns represent elements that have the same number of valence electrons and share similar chemical and physical properties

Ionic Compound

Composed of metal cations and non-metal anion, also known as a salt. Conducts electricity in solution (aq) High melting points

Unsaturated hydrocarbon

Contain carbon-to-carbon double or triple bonds.

Mendeleev

Created the first periodic table. Arranged elements by increasing atomic mass

Vapor Pressure Table H

Dotted line represents the boiling point of the 4 liquids at Standard Pressure of 101.3 kPa

Nonpolar bonds and nonpolar molecules

EN # difference between elements = 0 Ex: diatomics Molecules have even distribution of charges and are symmetrical.

Avogadro's Hypothesis

EQUAL VOLUMES of any gases at the same temperature and pressure contain EQUAL # OF MOLECULES

valence electrons

Electrons on the outermost energy level of an atom

Metalloids

Elements along the staircase. Have properties of both metals and nonmetals. Ex: Silicon

Nonmetals

Elements that are poor conductors of heat and electric current. Most are gases, dull & brittle

Breaking a Bond

Endothermic; Energy is absorbed (energy is a reactant) Ex: H20 + 571 kJ --> H2 + O2

Activation Energy

Energy required to initiate both Exothermic and Endothermic reactions.

Ionization Energy (IE)

Energy required to remove an electron from an atom

Conservation of Mass

Equal # of atoms on both sides of a chemical equation

# of protons

Equals # of electrons in a neutral atom

Atomic number

Equals the number of protons in the nucleus (never changes)

Making a Bond

Exothermic; Energy is released (energy is a product) Ex: Cl + Cl --> Cl2 + 242 kJ *more energy released the more stable the bond

Collision Theory

For a reaction to occur, the particles must collide with the appropriate orientation, and sufficient energy.

Transition Metals

Form colored ions in solution. Have multiple oxidation states

Rutherford

Gold foil experiment: (atom is mostly empty space, atoms contains a dense, positively charged nucleus); discovered protons.

Democritus

Greek philosopher that said all matter is made of tiny particles called "atomos" or atoms

Alkali Metals

Group 1 on PT. One valence electron that is easily removed to form a POSITIVE IONS. Highly reactive and form stable compounds.

Halogens

Group 17: Nonmetals 7 valence electrons in it's outermost shell. Very reactive. Many diatomic gases and Iodine solid

Noble Gases

Group 18: Nonreactive family of nonmetals; 8 valence e- (full octet). All are gases at room temp.

Alkali Earth Metals

Group 2 on PT. Two valence electrons, form +2 ions. reactive

diatomic molecules

H2,O2,F2

Ideal gas

HIGH Temp & LOW Pressure

Gas Laws: Volume-Pressure

If V increases, P decreases and If V decreases, P increases "Marshmallow man"

Gas Laws: Volume-Temperture

If V increases, T increases, and If V decrease, T decreases "soap souffle"

Factors that effect solubility

Increase in Temp, stirring, & particle size (increased surface area) will all increase solubility and increase rate of reaction.

Catalyst

Lowers the activation energy needed to get a reaction started.

Low IE and Low EN

Metals

Wave Mechanical Model

Modern model of the atom, atoms have electrons in "orbitals" that are like clouds around the nucleus

High IE and High EN

Nonmetals

Chemical symbol

One capital letter, or a capital letter and a lower case letter together. Mass on upper left side, and atomic # on lower left side.

Combined gas law

P1V1/T1 = P2V2/T2 Temp always in K STP = standard temp (273 K) and standard pressure (1 atm or 101.3 kPa)

Periods of periodic Table

Rows correspond with # of total principle energy levels "shells" (rings)

Atomic Radius

Size of the atom. Increases in size from more shells or if atom gains electrons (anion). Decreases in size if atom loses electrons (cation) or less shells.

Organic Chemistry

Study of all chemicals containing carbon

Heat of Reaction

The difference in energy between the PE of the reactants and PE of the products of a chemical reaction.

Colligative Properties

The more particles that are produced when a substance dissolves, the higher the BP and the lower the FP will be produced. Ex: *NaCl = 2 particles (Na+, Cl-) *CaCl2 = 3 particles (Ca+, Cl-, Cl-)

Polar bonds and Polar molecules

Uneven sharing of electrons causes a nonsymmetrical shape. EN # difference between atoms is above 0 Ex: WATER

Writing Ionic compounds

Write each element with their charge and CROSS & DROP numbers ONLY. Ex: Ca+2 Cl-1 --> CaCl2 *metal always is first.

Alkyne

a carbon compound with a carbon-carbon triple bond.

Ionic Bond

a chemical bond in which a METAL atom loses an electron to form a positive cation and a NONMETAL atom gains an electron to form a negative anion. "electrons are transferred"

Alkane

a hydrocarbon containing only single covalent bonds

Network Solids

a solid in which all of the atoms are covalently bonded to each other. C-C-C-C "diamonds"

(aq)

aqueous mixture, a substance is dissolved in water

Soluble

capable of being dissolved in some solvent (usually water)

Covalent/Molecular Bond

chemical bond formed when 2 atoms share electrons NONMETAL to NONMETAL

Bright line spectrum

colors produced when electrons fall to a lower energy level and release energy in the form of light.

Ketones

contain C- (C double bond O)- C functional group: ends in "one"

Organic Aldehydes

contain CHO functional group: ends in "al"

Organic Alcohol

contain OH functional group; ethanol, methanol

chemical property

describes how matter reacts when it changes chemically into another substances. Ex. reactivity with acid, base or with air to rust, flammability, decomposition.

Lewis dot structures

diagrams that show valence electrons as dots

Modern Periodic Table

elements are arranged in order of increasing ATOMIC NUMBER

Principle Energy Levels

energy levels of an atom "shells". Energy increases further from the nucleus

Average Kinetic Energy

is directly proportional to temperature. Highest Avg KE = Highest Temp

Metals

malleable (made into thin sheets) and lustrous (shiny) good conductors of electricity and heat.

Neutrons

neutral partical that has the same mass as a proton and is found in an atom's nucleus.

Bromine (Br) and Mercury (Hg)

only two liquids on the periodic table

sublimation

phase change from (s) --> (g)

gases

physical property most all nonmetals and group 18

filtration

process to separate a solid "precipitate" from a liquid

molecule

two nonmetal atoms combined form a covalent compound called a

JJ Thomson

used the cathode ray tube to discover electrons

properties

used to identify or recognize matter (objects).

gas

will uniformly and completely fill a container