College Chem Ch.2

What happened in 1000 BC

chemistry was used to mix and melt metals to make stronger weapons

Who was the first to come up with the idea that atom is the smallest indivisible part of particles?

The Greeks

Democritus

cretited with the word Atomos

Alchemy

an ancient traditional branch of natural philosophy and a precursor to modern chemistry that focused on turning basic metals into gold, curing diseases, and extending life indefinitely

Law of Conservation of Mass

Mass is neither created nor destroyed

Who created the law of conservation of mass

Antoine Lavoisier

Law of definite Proportions

A given compound always contains exactly the same proportions of elements by mass

Who created the law of definite Proportions

Proust

Law of multiple proportions

Elements will always combine in whole number ratios

who created the law of multiple proportions

John Dalton

What are the four postulates of Daltons Atomic Theory

Each element is made up of tiny particles called atoms, The atoms of each element are identical, Chemical compounds form when different atoms of elements combine, Chemical reactions involve reorganization of the atoms

JJ Thompson

credited with the charge of the electron using his cathode ray tube experiment

Milikan

Credited with finding the mass of an electron to be 9.11×10^-31 kg, using his oil drop experiment

Rutherford

credited with finding that the atom has a small, solid, positively charged center called a nucleus

Cathode ray tube experiment

he used a vacuume sealed glass tube with the ends attatched to a positive anode and a negative cathode, he shot electrons through the tube from the cathode. He put a positively charged plate at one end of the tube and a negative plate at the other end, the light beam made by the electrons bent upward towards the positive end, making the electrons have to be negative.

Oil Drop Experiment

Milikan sprayed oil through an atomizer, the droplets then fell through a pinhole into a chamber with two metal plates one positive the other negative, He then put x-rays through the field making the oil droplets catch free electrons and become negatively charged, from there he could control the voltage of the metal plates and adjust how the droplets moved, he measured how fast the oil fell to calculate its mass.

gold foil experiment

shot a beam of positive alpha particles through a thin peice of gold foil, thought that maybe a couple alpha particles might stray a little bit away but most would go right through. Most did go right through but some hit something and strayed farther than expected (they hit the nucleus)

current view of an atom

A tiny nucleus and electrons moving around it

what is a nucleus made up of

protons and neutrons

What is the Atomic number of an atom

the number of protons in the atom

what is an isotope?

Atoms with the same number of protons, but different number of neutrons in the nucleus

what is the mass number

the total number of protons and neutrons

what are the three isotopes of hydrogen?

protium (1 proton, 0 neutrons), Deuterium ( 1 proton, 1 neutron), Tritium ( 2 protons, 1 neutron)

what are groups/ families on the periodic table

Vertical columns

what are periods on the periodic table

Horizontal rows

What is Electron Affinity

the amount of energy released when an isolated, neutral gaseous atom gains an electron to form a negative ion

What is Ionization energy

the minimum amount of energy needed to remove an electron from a gaseous atom or ion

what is Coulombic attraction

the pulling force between particles with opposite electrical charges

What is Atomic radius

the total distance from an atom's central nucleus to the outer boundary of its surrounding electron shell

Metals

Cations, conducts electricity, malliable, ductile

Non metals

Anions, mostly gases and liquids

Semi metals

have properties of both metals and nonmetals, ex. silicone

what is a chemical bond

Forces that hold atoms together in a compound

Covalent bond

results from atoms sharing electrons or between nonmetals, called molecules

Ionic bonds

results when there is an attraction between oppositely charged atoms (ions) or between a metal and a nonmetal

why do cations occur

because an electron is lost

why do anions occur

because an electron is gained

why are atoms charged

because they are made up of naturally charged particles ( protons, electrons, & neutrons)

What is an acid

Any ironic compound that has hydrogen in the beginning of it