Chem 101

Unit 1

Daltons Atomic Theory

Atoms from one element can’t be converted to atoms of another element but they form specific ratios with other atoms to form compounds

Proton (p+)

Relative charge (+1)

Mass (AMU) = 1.0073

Neutron

Relative charge is 0

Mass (AMU) = 1.0087

Electrons e-

Relative charge -1

Mass (AMU) = 0.0005486

X value is atomic symbol

A value is mass number = protons + neutrons

Z value is the atomic number = number of protons

Number of neutrons

Is calculated by A - Z

Isotopes

Same number of protons (Z) but different mass number (A) b/c they have different number of neutrons

Average Atomic Mass

Atomic mass = sum of isotope mass x fractional abundance

sum of (m₁)(x₁)

Mass is in AMU

When do radioactive elements start

Starting with palladium (Pd)

Ion types

Cations - positive ion - e- removed

Anions - negative ion - e- added

11p 12n 10e

Sodium (Na+) ion

17p 18n 18e

Chloride (Cl-)

How to identify species

Use neutrons to find element and find difference in e and p to find ionic charge

Ionic compounds (Binary)

Metal and nonmental - cation first then anion

Add -ide to end of anion (CO2)

Meaning of roman numerals in Copper (ll) telluride

Means copper has a 2+ charge

What roman numerals go in FeCl3

Iron (lll) Chloride

NaClO

Sodium hyopchlorite

Polyatomic naming table

Strontium Iodate

Sr(IO3)2

Binary Compounds

Non metal + non metal and are written in order of increasing electronegativity

• add -ide to the end of second element

N2O

dinitrogen monoxide

Dichlorine heptoxide

Cl2O7

SF6

Sulfur hexafluoride

Dihydrogen monoxide

H2O

Binary acids

Contains no Oxygen

HCN(aq)

Hydrocyanic acid

HF(aq)

Hydrofluoric acid

Hydrosulfuric acid

H2S(aq) - sulfur has -2 charge - need 2 H

Oxyacids

Contain H + O + nonmetal

Oxyacids increase in O

1. Hypo_ous acid - hypo_ite

2. _ite - _ous acid

3. _ate - _ic acid

4. per_ate - per_ic acid

HClO2

Chlorous acid

HClO3

Chloric acid

HClO4

perchloric acid

Nitric acid

HNO3

Periodic acid

HIO4

hypobromous acid

HBrO

sulfurous acid

H2SO3

units of frequency

s^-1 or Hz

Amplitude

height of crest or trough and is related to the intensity of the radiation

Equation for speed of wave

c= lamda multiped by v

Blackbody radiation

EM radiation emerging from a blackbody (smoldering coal) gives a spectrum that cannot be explained by treating light as a wave

Change in energy of an atom equation

Physical explanation of blackbody

each atom emits only certain quantities

Quanta

Absorbed or emitted by an atom when there is a change in energy which is = hv

Energy of a photon

= hv = hc/wavelength

Spectral lines

are produced when an electron moves from one energy level to another

Work function

minimum energy required to remove an electron from the surface of a material in a vacuum

1/wavelength = R(1/(n1² - 1/n2²)

Rydberg equation where R = 1.097 × 10^7 m^-1

En = -R_H(Z²/n²)

Different version of Rydberg equation but finds energy rather than wavelength

Z is the number of protons in the nucleus

Ground state

electron is in its first orbit - lowest possible energy

excited state

any orbit further from the nucleus - n>1

n=2 first excited state

n=3 second excited state

…

In the rydberg equation if n = infinity what is the approximate energy of the photon

About 0 because n is on the denominator in the equation and all answers will approach closer to 0

Infrared series

Starts at n= 4 or higher and goes to n=3 (second excited state)

Visible series

When electrons drop from outer orbits (n=3 or higher) to the n= 2 orbit (first excited state)

Ultraviolet series

When electrons drop to n= 1 (ground state)

H-like species

Hydrogen like species - one electron species

X^+(Z-1)

n

any positive integer and is the size of the orbital

L (angular momentum)

0 to n-1 and is the shape of the orbital

one or more sublevels denoted by L

Equation for energy level

orbitals

s p d f

mL

limited by values of L and is spatial orientation of orbital

-L thru 0 to +L

-L, (-L+1)… 0, … L

total number of mL values is calculated by 2L+1

L = 2

d orbital

L = 1

p orbital

L = 0

s orbital

L = 3

f orbital

s orbitals

p orbitals

d orbitals

d orbitals

2pz orbital

mL = 0

L = 2 mL = 0

3dz²

number of radial nodes

n - L - 1

to change from 1s to 2s orbital

add + sign in first shell and - sign in second

not charges just notation for radial node

paramagnetic species

unpaired electrons

diamagnetic species

all electrons are paired

Z_eff in cations

Increases as there is a net positive charge 

Smaller than atoms

Radius decreases

Z_eff in anions

Larger than atoms

Decreases as there is a net negative charge

Radius Increases

Down a group

Ionic size increases because n increases

Across a period

Ionic size decreases with increased positive charge

How to define size of an atom

Atomic radius is half the distance between 2 centers 

extent of the spherical contour (90% probability of finding an electron)

What happens when Zeff increases

the outer electrons are pulled closer to the nucleus which decreases atomic size

Ionization Energy

Energy that must be added to remove an electron

First Ionization energy

outermost electron removed

If an electron is removed what happens to Zeff

Zeff increases 

More energy is required to to remove next electron because it is tighter together 

IE increases 

Across a perid IE ….

increase

down a group IE …

decreases

Exceptions to IE increasing

O and Be

Have slightly different electron configurations

electron affinity 

energy change when a GASEOUS atom or ion gains an electron

across a period EA ..

increases with some exceptions

N EA₁ is positive instead of negative because it starts very stable and you add an electron

Be too

down a group EA …

decreases with some exceptions

unlike alkali metals…

hydrogen shares its electrons with nonmetals instead of transferring it

H-

Hydride - not common and very reactive