concepts of matter

principle quantum number (n)

can have integral values from 1 - infinity

angular momentum/azimuthal quantum number (ℓ)

tells us the shape of the orbital

value of ℓ depends on..

the value of n, ranges from 0 to n-1

ℓ is designated by the letters s, p, d, f, etc.

magnetic quantum number (mℓ)

describes the orientation of the orbital in space

value of (m sub ℓ)

ranges from -ℓ to +ℓ including 0

spin quantum number (m sub s)

either +1/2 or -1/2, indicating the spin orientation of an electron

scientist credited with the development of the periodic table

Dimitri Mendeleev

how were the elements arranged in Dimitri's periodic table

in terms of increasing atomic weight

spots for no elements on the periodic table

left blank, but Dimitri made predictions about the properties the element would have if it was discovered (a significant number of them came true due to the periodic law at the time)

old periodic law

when the elements are arranged in terms of increasing atomic weight, certain chemical and physical properties will re-occur

how are elements arranged in the modern periodic table?

in terms of increasing atomic number

horizontal row in the periodic table

period

vertical columns on the periodic table

groups/families

# of groups

18 groups

- 8 "A" groups

- 10 "B" groups

"A" groups

main group of elements or the representative groups

"B" groups

transition metals

# of periods

7 periods

as you go from left to right on the periodic table, you go from...

metal → semi-metal/metalloids → non-metal

semi-metal exceptions

aluminum (definitely a metal) & polonium (a radioactive metal)

- the rest of the elements are non-metal

group 1A

alkali metals

group 2A

alkaline earth metals

group 3A-6A

transition metals

group 7A

halogens

group 8A

inert gases

periodic properties

- atomic radius

- ionization energy

- electron affinity

- electronegativity

atomic radius

refers to the size of an atom

atomic radius trend

increases down a group, decreases across a period

- atomic number increases, # of quantum levels remains the same

atomic radius; going across the period results in..

a greater net force that penetrates to the valence electrons

atomic radius; net force/effective nuclear charge

the electrons in the core absorb some of the force from the nucleus

Zeff

effective nuclear charge

Zeff, Z=

atomic number

Zeff, eff=

effective

when does Zeff increase?

going across the period

- pulls the valence shell and its electrons closer in to the nucleus, resulting in a decrease in radius

when do the atomic numbers & # of quantum levels increase?

as you go down the group

added quantum levels

- primarily responsible for the observed increase in radius as you go down the group

- results in a larger core and the electrons in the core absorb some of the force from the nucleus

shielding effect

absorption of force by the electrons in the core, resulting in a decrease in Zeff

ionization energy

energy required to remove an electron/electrons from the valence shell of a gaseous atom

ionization energy trend

increases across the period, decreases down the group

reasons for ionization energy trend

as you go across the period, atomic radius is smaller, attractive force on the valence electrons is greater

how many ionization energies can an atom have?

as many as it has valence electrons

electron affinity

energy change that occurs when an electron/electrons are added to the valence shell of a gaseous atom

electron affinity trend

increases across a period & becomes more exothermic, decreases down a group and becomes more endothermic

electronegativity

ability of an atom to attract shared electrons to itself

Pauli's exclusion principle

states that no 2 electrons in an atom could have the same set of 4 quantum numbers

- the first 3 quantum numbers can be the same as the 4th which is the spin quantum number that must be different

↑

represents clockwise spin

↓

counter clockwise

Hund's rule

states that electrons in an atom tend to occupy degenerate orbitals singly in the same direction

degenerate orbitals

orbitals that have the same energy

how does an orbital become degenerate?

must have the same principle energy level and sub-level

De Broglie wave theory

theorized that particles hold the same properties as waves

De Broglie's equation

λ = h/mv

quantum model

according to this model, orbitals are regions of probability for finding electrons

quantum model; shells

principle energy levels/principle quantum levels

principle energy levels are designated with the letter ___

n, where n has integral numbers ranging from 1 to infinity

sub-levels of principle energy levels

s,p,d,f,g

energy of the principle energy levels

1 < 2 < 3 < 4 etc.

energy of the principle energy sub-levels

s < p < d < f < g

principle energy sub-levels are comprised of...

orbitals, it is in the orbitals that the electrons exist

electron configuration

shows the distribution of electrons in terms of principle energy levels, sub-level, and # of electrons present in the sub-level

# of electrons in a sub-level

restricted to being ≥ the maximum it could hold

afbau principle

the filling of the sub-levels, filling a level before going to the next

exceptions to the order of filling

when is energy released in the form of light?

when an electron moves from a high energy level to one of lower energy

2 types of spectra

- continuous

- line

continuous spectra

pattern obtained when light from a mixed source is analyzed (e.g sunlight)

line spectra

pattern obtained when light from a pure light source (single element) is analyzed (e.g neonlight)

2 theories about light

- wave theory

- particle theory

electromagnetic waves

formed as a result of vibrations in an electric & magnetic field

bohr equation

-2.18 x 10 ^18 J

rydberg equation

1/wavelength = R (1/n1^2 - 1/n2^2)

matter

made up of tiny particles called atoms, an atom being the smallest unit of an element

2 basic units of an atom

protons & neutrons

protons (P+)

positively charged subatomic particles

- found in the nucleus of the atom

# of protons in an atom

atomic number (Z)

neutrons (n°)

neutral subatomic particles

- found in the nucleus of the atom

# of protons + # of neutrons

mass number

mass of protons & neutrons

1 amu

atomic mass (atomic weight)

weighted average of the mass of the different isotopes for that element

isotopes

atoms of the same element with the same atomic #, but different mass #

average atomic mass

(% abundance of mass isotope 1) + (% abundance of mass isotope 2) + etc.

calculating % abundance

(x) (% abundance of mass isotope 1) + (1-x) (% abundance of mass isotope 2)

let x = the decimal for 1 isotope

chemistry

study of matter & the changes it undergoes

matter

anything that has mass & takes up space

mass

measure of the amount of matter that a body contains

-

weight

subject to change; where there is no gravity, there is no weight

how does the concept of mass differ from weight?

mass is a measure of the amount of matter in an object, while weight is a measure of the effect of gravity on that object.

why doesn't mass change?

it is measured to a known standard

measurements

activity conducted to determine the quantity of the matter you have

the reliability of any measurement depends on:

- the instrument used

- the person conducting the measurement

matter is categorized into:

- pure substances

- mixtures

pure substances

compounds & elements

compounds

can be decomposed into simpler substances

elements

cannot be decomposed into simpler substances

mixtures

homogeneous & heterogeneous

3 basic states of matter

solid, liquid, gas

what determines the state of matter?

depends on how close the molecules that make up matter are to each other

gas → liquid

condensation

liquid → gas

evaporation

solid → liquid

melting