College Chemistry Exam 1

Matter

Anything that has mass and takes up space

Scientific Method

A series of steps followed to solve problems including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions.

Francis Bacon

developed the scientific method

Empiricism

the view that (a) knowledge comes from experience via the senses, and (b) science flourishes through observation and experiment.

substance

a form of matter that has a definite composition and distinct properties

Element

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

Mixture

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

homogenous mixture

Composition of the mixture is the same throughout.

heterogeneous mixture

Composition is not uniform.

Compound

Substance composed of atoms of two or more elements chemically united in fixed proportions

States of Matter: Solid

Molecules are held close together in an orderly fashion with little freedom of motion.

States of Matter: Liquid

Molecules are close together but are not held so rigidly in position and can move past one another.

States of Matter: Gas

Molecules are separated by distances that are large compared with the size of the molecules

physical change

Appearance changes, but identities of the substances do not change, generally within the same state.

chemical change

substances are transformed into new substances with different properties

Atoms

Matter is made of tiny, indivisible particles

law of definite proportions

A compound is made up of elements in the same proportion by mass, atomic ratios in a compound will also stay the same.

Law of Conservation of Mass

Matter is not created nor destroyed in any chemical or physical change

What are atoms made of?

protons, neutrons, electrons

Proton

positive charge, makes atomic charge

Neutron

no charge

Electron

negatively charged particle

Nucleus

Center of an atom

mass number

the sum of the number of neutrons and protons in an atomic nucleus

Discovery of an electron

J.J. Thompson with a cathode ray tube, determined ratio of electric charge to mass of electron

Discovery of an electron

R.A. Millikan with the oil drip, charge on each electron is exactly the same

Discovery of Proton and Nucleus

Rutherford gold foil exp., charge on each electron is exactly the same.

Discovery of the neutron

James Chadwick, proposed positively charged particles in the neclues

Quantum

the smallest unit of energy that can be emitted in electromagnetic radiation.

wavelength

reverse roygbiv

frequency and energy emission

roygbiv

quantum dot size

reverse roygbiv

Isotope

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

Atomic #

# of protons

Mass #

protons + neutrons, with charge number of electrons changes

atomic weight

weighted average of masses of all the isotopes of an element.

mole

a unit of counting, that tells us how many atoms are in a set amount, 6.022x10^23

molecular mass

adding together all atomic masses

atomic mass

mass of specific element

percent composition

(mass of element/ total mass of compound) x 100%

empirical formula

percent x (mol/atomic weight)

wavelength vs frequency

inversely related

photoelectric effect

energy above a certain threshold frequency can eject electrons from metal surfaces and reflect light. Both wave and Particle

atomic emission spectrum

Pure elements in the gas phase emit line spectra - i.e., they emit light only at specific wavelengths

principal quantum number

symbolized by n, indicates the main energy level occupied by the electron

angular momentum quantum number

symbolized by l, indicates the shape of the orbital

magnetic quantum number (m sub l)

an integer that specifies the orientation of an orbital

Electron Spin Quantum Number

spin up 1/2 or spin down 1/2

Electron Shielding

position in relation to the nucleus changes for electrons in higher energy orbital

Paramagnetism

unpaired electrons

diamagnetism

paired electrons in electron configurations

effective nuclear charge

the net positive charge experienced by valence electrons

electronegativity trend

increases across a period, decreases down a group, up and right

ionization energy trend

decreases from top to bottom in a group; increases from left to right in a period

atomic radius trend

decreases from left to right
increases from top to bottom

Ionic Radius Trend

adding anions (add electron) increases radius, removing electron (cation) decreases radius