Atomic theory

When did the Greeks for their theory?

400 BC

What did the Greeks believe?

They believed that all matter was made up of the four fundamental substances. 

What are the 4 fundamental substances?

Earth, wind, fire, air

Who believed that all matter was made of of Atomos?

democritus

What are atomos?

tiny, small, invisible particles

When did the alchemists form their theory?

2000 years after the greeks

What were alchemists obsessed with?

turning metal into gold

What did alchemists discover?

Hg, S, Sb (antimony) and how to prepare acids (laid the ground work for modern day chemistry)

Who was john dalton?

an english science teacher

What did Dalton review?

early observations of 18th century scientists

What is the law of definite composition?

a given compound always has same proportion by mass of elements 

What was part 1 of daltons atomic theory?

all matter is composed of extremely small particles

Part 2 of daltons atomic theory?

atoms of a given elements are identical is size, mass, and other properties.

Part 3 of daltons atomic theory?

atoms of different elements different in size, mass, and other properties. 

part 4 of daltons anatomic theory?

atoms can not be subdivided, created, or destroyed in a chemical reaction

what law pairs with part 4 of daltons atomic theory?

law of conservation of mass- lavoisier

part 5 of daltons anatomic theory?

atoms of different elements combine i simple whole number ratios to form chemical compounds. 

what law pairs with part 5 of daltons anatomic theory?

law of composition and definite proportions

What was daltons error?

elements CAN have atoms with different masses

what is an isotope?

atoms with the same number of protons but different number of neutrons and mass

What is average atomic mass?

average of all isotopes for a specific element

what does average atomic mass depend on?

relative abundance of each isotope

How do you calculate average atomic mass?

(mass 1 x abundance 1) + (mass 2 x abundance 2)

When were elections discovered?

in late 1800’s, it was showed that cathode rays were composed of negatively charged particles

Who created crookes tubes and cathode rays

jj thomson

how did thomson discover electrons?

electrons jumped off the cathode when a positively charged magnet deflected particles showing the the particle inside were negative. 

What is the plum pudding model?

claims that electrons are found in a sphere of positive charges

How was the nucleus discovered?

ernest rutherford formed the gold foil experiments. particles should have passed through without deflection if plum pudding model was true but instead particles deflected because they came in contract with protons and neutrons.

what did the greeks believe?

all matter was made of the 4 fundamental elements: earth, wind, fire, water

what were the alchemists interested in?

turning metals into gold; discovered Hg, S, Sb

what did john dalton do?

he created atomic theory

what was wrong with daltons atomic theory?

part 2, atoms of the same element can have different masses; called isotopes

How did JJ Thomson contribute to the atom?

he discovered the electron

how did JJ Thomson discover the electron?

used a glass tube, called a crooks tube, with a cathode ray running from a positive to negative side. Thomson placed a positive magnet on the outside, which bent the ray towards the positive side, revealing that the cathode ray was made of negatively charged electrons

what is the plum pudding model?

a model of the atom that depicted electrons floating in a positively charged “pudding”

what was the gold foil experiment?

an experiment performed by Ernest Rutherford where a piece of gold foil was placed inside a detector. alpha particles were then shot at the piece of foil. Rutherford believed that if the plum pudding model was right, than the alpha particles would travel through the foil smoothly, landing directly on the other side. What he discovered was that the alpha particles path was interrupted, causing them to ricochet. This lead to the discovery of the nucleus. 

what was the planetary model?

a model of the atom what shows electrons orbiting a positively charged nucleus (like a solar system)

what was the bohr model?

a model of the atom where electrons orbit a central nucleus in specific, fixed paths called energy levels or shells, similar to planets orbiting a sun (more organized) (gave lanes for electrons)

what did the bohr model propose?

proposed that electrons orbit the nucleus in rings

what does each ring of the bohr model represent?

an energy level

what happens if an electron comes in contact with energy?

it jumps up a ring

what happens when an electron falls down a ring?

it released a photon, in essence, releasing color

how do we know what color a photon releases?

it is opposite of color that is absorbed

what do transitions depend on?

number of rings jumped

what are transitions?

the movement of an electron from one fixed energy level (orbit) to another

1 statement of bohr model

hydrogen atoms exist in only specified energy states. the atom is quantized

what does it mean if an atom is quantized

properties like its electrons' energy can only exist at specific, discrete levels, not as a continuous range

2 statement of bohr model

hydrogen atoms can absorb only certain amounts of energy

3 statement of bohr model

when excited H atoms lose energy, they lose only certain amount of energy

4 statement of bohr model

energy is emitted as photons

5 statement of bohr model

the different photons produce different color emission lines

6 statement of bohr model

the greater the jump, the greater the energy of the photons

7 statement of bohr model

electrons can only circle in allowed orbits

8 statement of bohr model

the higher the energy of the electron, the further away it is from the nucleus

what is heisenburgs uncertainty priciple?

states that you can’t know position and momentum of an electron at the same time

what did Schrödinger discover

4 quantum states of atom, further developed the idea of energy levels for atoms instead of orbits; used wave mechanics

principle quantum number

energy level

angular quantum number

shape (s, p, d, f)

magnetic quantum number

orientation: sx, py, fx, dz

aufbau principle

lowest energy level orbital is always occupied first

hunds rule

electrons don’t pair unless they have to

pauli exclusion

in an atom, no two electrons have the same quantum number (in orbital notation, can’t have 2 up (or 2 down) arrows on the same line

what are protons?

positively charged subatomic particles found in the nucleus of every atom (mass of 1)

what are electrons?

negatively charged subatomic particles that orbit the nucleus of an atom in orbitals (mass of 0)

what are neutrons?

electrically neutral subatomic particles found in the nucleus of every atom, except for hydrogen (mass of 1)

what does atomic number mean?

number of protons

how to find number of neutrons?

neutrons and protons add up to atomic mass

how to find the number of electrons

unless it tells you the charge, the number of protons is the same as electrons

how to determine charge?

difference between number of electrons and protons

how to calculate average atomic mass?

mass 1 (abundance 1) + mass 2 (abundance 2)

How to calculate wavelength?

speed of light/ frequency

how to calculate frequency?

speed of light/wavelength

how to calculate energy of wave?

Planck's constant times frequency

relationship between wavelength, frequency and energy

energy is directly proportional to frequency and inversely proportional to wavelength

what are the d-block exceptions?

if a orbital notation or electron configuration ends in d4 or d9

orbitals

s, p, d, f

shape of s orbital

spherical

shape of p orbital

dumbell

shape of d orbital

four-leaf clover shape

shape of f orbital

complex and highly irregular

energy levels

1-7

rule for d orbital

one fewer than s orbitals

rule for f orbital

2 fewer than s orbital

what are valance electrons

electrons on last rings

groups 1-2 and 13-18 valence electrons

1, 2, for 1-2

3-8 for 13-18

valence electrons for d orbitals

every element has 2 unless it is in 3d4, 3d9, 4d4, 4d9, 5d4, 5d9, 6d4, 6d9, then they have 1 valence electron

what does isoelectronic mean?

same # of electrons, different number of protons

what color of light has the highest frequency

violet

what color of light has the longest wavelength

red

what are isotopes

atoms with same number of protons but different number of neutrons and mass

what happens if you change the number of protons?

you change the element

what does nuclear chemistry study?

studies the properties of atomic nuclei and their reaction

what is alpha decay?

radioactive decay of an atomic nucleus by emission of an alpha particle 

what happens during alpha decay

atomic number decreases by 2, mass decreases by 4

what is an alpha particle

a helium particle with an atomic mass of 4 and an atomic number of 2

what is beta decay?

the radioactive transformation of an atomic nucleus accompanying the emission of an electron

what does beta decay involve?

unit change of atomic number but none in mass number, also called beta transformation

what happens during beta decay?

one neutron changes and becomes a proton, causes an increase in proton, the mass difference is an electron, so electron is spit out; atomic number goes up mass stays the same

positron decay

the antiparticle of the electron, having the same mass but an equal and opposite charge

what happens during positron decay?

loses a positive electron, mass doesn’t change, atomic number goes down by one, proton becomes neutron and spits out an electron