Chemistry - Unit 3

(I recommend answering with the term)

Orbital

3-dimensional region of space where there is a 90% chance of finding an electron

The energy of electrons is…

quantized

n

describes the main energy level in which an electron is located

Wavelength

lamda, length of a wave (m)

l

describes the shape of the orbital (sublevel)

range of l

0 to (n-1)

l=0

s-sublevel

s-sublevel

sphere, one orbital

l=1

p-sublevel

p-sublevel

dumbell, three orbitals

l=2

d-sublevel

d-sublevel

double dumbbells, five orbitals

l=3

f-sublevel

f-sublevel

funky shape, seven orbitals

superposition

a particle can take on two different states at the same time, only able to differentiate in observation

m

describes the number of orbitals per sublevel (orientations)

m_s

describes the “spin” of an electron, what position it takes on (wave or particle)

entangled electrons

connected, cannot have the same form/spin at the same time

Pauli Exclusion Principle

maximum of 2 electrons per orbital (each with opposite spins)

Aufbau Principle

Electrons will occupy the lowest energy orbital available

Frequency

nu, number of waves that pass a fixed point in 1 sec (1/s=Hz)

Valence electron

electron in the outermost energy level (involved in bonding)

Electron Configuration & Orbital Diagram

show how electrons are arranged in an atom

Energy

the difference in energy levels (J)

Speed of light

all wave energy travels at c

Excited electrons

electrons move from ground state to excited state, releasing a photon of light when moving back down to ground state

type of light

depends on the energy difference between the excited and ground states

Constructive interference

double slit experiment’s interference pattern where crest meets crest (brightest)

destructive interference

interference pattern where crest meets trough, cancel out, no amplitude (brightness)

amplitude

height from middle of wave, determines brightness, more amplitude —> more brightness 

photoelectric effect (planck & einstein)

emission of electrons from light hitting metal, higher frequency, higher energy electron

line emission spectrum

revealed when light composed of many different photons is passes through a prism, each line is produced by a different photon when an electron goes from excited —> ground state

Heisenberg Uncertainty principle

It’s impossible to determine with certainty both the position and momentum of a particle 

Periodicity

repeating pattern

Dmitri Mendeleev (1870 Russia)

Arranged known elements by increasing atomic mass and similar properties, leaving empty spaces for elements that hadn’t been discovered yet

Henry Moseley (1910)

Arranged elements by number of protons

Groups of periodic table

columns of the periodic table (1-18), same group have similar chemical properties and same number of valence electrons

chemical properties

determined by number of valence electrons

Periods of periodic table

Rows of the periodic table (1-7), same period same valence energy level (greatest n)

Alkali metals

group 1 (not H), soft metals, very reactive, form 1+ ions (ns¹), wanting to become a noble gas, react with water to form a base and hydrogen gas

Alkaline earth metals

group 2, metals, stronger and denser than alkali metals, form 2+ ions (ns²)

Halogens

group 17, non-metals, “salt makers”, highly reactive, 7 valence electrons (ns²np⁵)

Noble gases

group 18, non-metals, 8 valence electrons (ns²np⁶), stable and unreactive, doesn’t form ions

metals

conduct heat and electricity, malleable, ductile, lusterous (left of metalloids)

ductile

drawn into a wire

nonmetals

poor conductors, brittle (right of metalloids)

metalloids (semimetals)

mixture of metallic and nonmetallic properties, “staircase” of periodic table

(B, Si, Ge, As, Sb, Te, Po, At)

Periodic trends

recurring patterns down a group or across a period

atomic radius

measures size of atom, ½ the distance between the nuclei of 2 like atoms joined together (pm)

atomic radius group trend

atom size increases down groups (top→bottom) due to electron shielding

electron shielding

inner electrons shield valence electrons from the nucleus’s attractive force

atomic radius period trend

atom size decreases across periods (left→right), due to nuclear charge

nuclear charge

as protons are added to the nucleus, the attractive force is stronger

ionization energy (E_i)

energy required to remove and electron (kJ/mol)

ionization energy group trend

E_i decrease down groups (top→bottom); electron shielding, more electrons further away from nucleus 

ionization energy period trend

E_i increases across period (left→right); increasing nuclear charge makes it more difficult to remove electrons

cations

positive ions (more protons)

anions

negative ions (more electrons)

cation ionic size

resulting ion is smaller, less electrons to protect others from nuclear attraction

anion ionic size

resulting ion is larger, less nuclear attraction, force isn’t as effective for more electrons

Diatomic elements

elements found in 2 atoms

Photon

particle of light, dual nature (superposition), absorbed by electrons

quantum of energy

the amount of energy absorbed or released by electrons to change energy levels