Honors Chemistry Midterm Review

review for holland's midterm

chemistry

chemistry

the study of the composition, structure, and properties of matter, the process that matter undergoes, and the energy changes that accompany these processes.

chemical

a compound or substance that has been purified or prepared

mass

the measure of the amount of matter in an object

matter

anything that has mass and takes up space

atom

smallest unit of an element that maintains the chemical identity of that element

molecule

smallest unit of a compound that retains the same properties of a compound

element

a pure substance that cannot be broken down into simpler, stable substances

compound

a pure substance that can be broken down into simple substances, made of more than one element

extensive property

depends on the amount of matter that is present. ex. volume, mass, or amount of energy in a substance

intensive property

does not depend on the amount of matter present. ex. boiling, melting, density, or the ability to conduct heat or electricity

physical properties

something we can observe and measure without changing the identity of the substance. ex. finding melting or boiling point, density

chemical properties

substance’s ability to undergo changes that transform it into different substances. ex. flammability, toxicity, acidity, reactivity

change of state

the change of a substance from one physical state to another

plasma

high-temperature physical state where atoms lose most of their electrons

mixture

a blend of two or more kinds of matter, each of which retains its own identity and properties

physical change

a change in a substance that does not involve a change in the identity of the substance. ex. grinding, cutting, melting, boiling

chemical change

a change in which one or more substances are converted into different substances. clues to this are color change, precipitation, and gas. ex. burn, corrode, rust, explode

AMU

atomic mass unit

conservation of mass

mass cannot be created or destroyed

Law of Definite Proportions

chemical compound always has fixed ratio by mass

Law of Multiple Proportions

when 2 elements combine, their ratio is in whole numbers

mole

6.02 x 10^ 23. unit for very small things in very large numbers

molar mass

mass of one mol of a substance, ex. 6 g/mol

isotope

atoms with the same number of protons but different numbers of neutrons

empirical formula

most basic ratio of elements in a compound

molecular formula

true ration of elements in a compound, unsimplified

ion

an atom in which # of electrons is not equal to the # of protons

anion

negatively charged ion

cation

positively charged ion

isoelectric

same charge

Democritus

Proposed that the world is made of tiny particles. Was the first person to come up with the idea of an atom

Aristotle

Believed matter was made up of five elements

John Dalton

English scientist who developed an atomic theory with five main postulates. Also the first to discover the properties of an atom

JJ Thomson

English scientist who discovered the electron using a cathode-ray tube, “Plum Pudding” Model

Robert A. Milikan

Determined the charge of an electron using the oil drop experiment

Ernest Rutherford

Discovered protons and the nucleus of an atom using the gold foil experiment. Also discovered that atoms are mostly empty space

Niels Bohr

His atomic model shows electrons in distinct energy levels, electron configuration

James Chadwick

Discovered the neutron, led to the atomic bomb

Frederick Soddy

Discovered the isotopes of elements

Henry Moseley

Linked the atomic number to the number of protons in the nucleus and that protons have a positive charge

Antoine Lavoisier

Father of modern chemistry, made it more quantitative as opposed to qualitative

Robert Bunsen

Invented the Bunsen burner, techniques in data collection with compounds and elements

Bohr Diagram

circular diagram showing electrons

Aufbau Principle

fill in lowest available energy level first

Pauli Exclusion Principle

• Each orbital can hold a max of 2 electrons

• Electrons must spin in opposite directions

• Arrows represent electrons

Hund’s Rule

Spread out electrons within an energy sublevel before pairing them up

6 branches of chemistry

organic, inorganic, physical, analytical, theoretical, biochemistry

atomic radius

one-half the distance between the nuclei of identical atoms that are bonded together. increases to the bottom and left

electronegativity

the tendency of an atom or a functional group to attract electrons towards itself. increases up and right

ionization energy

the amount of energy required to remove an electron from an isolated atom or molecule. increases up and right

electron affinity

the amount of energy released when an electron attaches to a neutral atom to form a negatively charged ion. increases up and right

period

The horizontal rows of chemical elements on the periodic table. Every element in a period have the same number of electron shells

group/family

The vertical columns of chemical elements on the periodic table. Each element in a group/family has the same number of valence electrons and have similar chemical and physical properties

precision

repeatable and reliable

accuracy

a correct measurement

homogeneous mixture

composition is uniform throughout, can’t be pulled apart. ex. juice, glue, milk

heterogenous mixture

composition is not uniform, can be pulled apart. ex. salad, chicken soup, sandwich

how to read a caliper

Line up jaws, keep big number, first aligning small number is decimal

Steps for scientific method

Observation, hypothesis, experiment, data analysis, conclusion (OH EDAC)

metals

good conductors for heat and electricity

nonmetals

poor conductors for heat and electricity

noble gases

inert, very stable, don’t form compounds

halogens

non-metals, strong odor, don’t dissolve well, react with most non-metals and metals

alkali metals

1 valence electron, very reactive, soft, stored under oil. form cations

alkaline earth metals

2 valence electrons, not as soft or reactive as alkali metals. form cations