Chemistry Unit Test 2

1 meter

1*10^-9 nm

average atomic mass equation

(mass 1)(% abundance/100)+(mass 2)(% abundance/100)

quantum jump

When electron jumps energy levels

atomic radius

one-half the distance between the nuclei of identical atoms that are bonded together (units: picometers 10^-12)

ionic radius

Distance from the center of an ion's nucleus to its outermost electron

electronegativity

tendency for an atom to attract another electron so it will covalently bond (no units but a value (0-4)

ionization energy

amount of energy required to remove an outer electron from a gaseous atom at ground state (units= Kilojoules)

more occupied energy levels

greater atomic radius and weaker force of attraction

Cation

positive charged ion

Anion

negatively ion

Dalton's Atomic Theory

- elements are composed of indivisible atoms.
- all atoms of a given element are identical; same mass, size, and chemical properties
- Atoms cannot be created, divided into smaller particles, nor destroyed.
- Different atoms combine in simple whole number ratios to form compounds.
- During chemical reactions, atoms are separated, combined, or rearranged.

protons

- found in the nucleus
- contribute to the mass number
- determine the atomic number

isotopes will have different amounts of

neutrons

neutrons

- have no charge
- found in the nucleus
- contribute to the mass number

What were known to Rutherford before his experiment?

electrons

What subatomic particles have the highest mass

protons and electrons

An ion is formed when an atom gains or loses

electrons

Discovered in the Cathode Ray experiment

electrons

mass number

protons + neutrons

atomic number

number of protons

J.J. Thomson concluded that

atoms contained mobile particles with a (-) charge

Thomson's Plum Pudding Model

An atom must be a sphere of positive charge with small negatively charged particles dispersed evenly throughout resulting in a neutral charge.

alpha particles

positively charged particles

Justifying Thomson's Model

If atoms are positive spheres with evenly distributed negative charges, then alpha particles will pass through a neutral atom undisturbed and undeflected.

Thomson's observations

- A beam traveling toward the positive electrode (anode) and curving upward toward the positive plate
- particles detected in many spots

Rutherford observations

- A very small number of alpha particles were deflected at large angles
- A smaller number of alpha particles were deflected almost directly back at the source
- Most of the alpha particle beam passed through the gold foil without deflection from its straight path
- Foils made from different metals produce the same results

Rutherford's conclusions

- The atom's positive charge and most of an atom's mass is located in a central region
- This central region must be dense and tiny. It is called the nucleus.
- The alpha particles did not encounter any matter or charge. Most of the volume of an atom must be empty space
- All atoms have similar distribution of positive charge and mass

metallic character

ability to lose electrons

ground state

The lowest energy state of an atom

excited atom

an atom in which an electron has moved from a lower to a higher energy level

what is the unit for frequency (ν)?

Hz, 1/s, s^-1

what is the unit for wavelength?

meters

what is the unity for energy

(J) Joules

quantum theory

there are only certain allowed energy states for an electron and these are quantized

atomic emission spectra

The discontinuous line spectra of light produced when excited atoms return to their ground state and emit photons of a certain frequency.

Each orbital has

2 electrons

s orbitals

1 orbital max 2 electrons

p orbitals

dumbell shape with 3 orbitals max 6 electrons

d orbitals

5 orbitals with max 10 electrons

f orbitals

7 orbitals, 14 electrons

g orbitals

9 orbitals, 18 electrons

h orbitals

11 orbitals, 22 electrons

Hund's Rule

before they can pair up, electrons occupy orbitals of the same energy (orbitals of a given sublevel) so that they all have the same spin direction.

Aufbau Principle

the lowest energy sublevels must first be filled before electrons can be placed in a higher energy sublevel.

Pauli Exclusion Principle

- an orbital can describe, at most, 2 electrons;
- to occupy the same orbital, two electrons must have opposite spins.

opposite spins

reduce repulsion= greater force of attraction

atomic orbital

probable location of an electron in a atom

As you go down the periodic table

elements become more metallic

as atomic radius increases

elements can lose electrons more easily making them more metallic

Metals

- lose valence electrons
- form positively charged cations
- good conductors of heat and electricity
- most are hard, maluable, and ductile
- solid at room temperature
- shiny when smooth and clean

Non metals

- gain electrons in valence shell
- gases are diatomic molecules
- poor conductors of heat and electricity
- form negatively charged anions

the only liquid that is diatomic is

bromine

the rest of the elements are solids including __________ which is diatomic

Iodine

what does bonding achieve

noble gas configuration to create full octets and gain stability reducing repulsion

Bohr vs Schrodinger

Schrodinger= more complex, utilized 3D shape of nucleus, more accurate and true to the electron model, hard to visualize

As you move across a period...

atomic radius decreases because there is a proton added and it pulls electrons closer.