Electrons, Protons, Neutrons Calculations:

• Electrons: negatively charged, located in the electron cloud outside of the nucleus

• Protons: positively charged, located in the nucleus

• Neutrons: no charge, located in the nucleus

• Mass of neutron ≈ Mass of proton

• amu: the unit for atomic mass

APE MAN

• Atomic # = # of protons = # of electrons

• Atomic Mass = Atomic # + # of Neutrons

Ex: 

Atomic mass = protons + neutrons

12 = 6 + neutrons

6 = neutrons / neutrons = 6

Bohr Model:

• Maximum of 2 electrons in the first energy level (n=1)

• Maximum of 8 electrons in the second energy level (n=2)

• Maximum of 8 valence electrons on the outermost energy level

valence electrons are electrons located in the outermost energy level

another way to say energy level is “shell”

Ions:

• An atom that bears one or more positive/negative electric charge

• Electric charge = protons - electrons

Ex: Calcium has 20 electrons and 20 protons. If we were to remove 1 electron from the calcium atom, it would have a +1 charge.

• 20 - 19 = +1

Ion notation: Ca⁺¹

Ex 2: Sulfur has 16 electrons and 16 protons. If we were to add 2 electrons to the fluorine atom, it would have a -2 charge

• 16 - 18 = -2

Ion notation: S^-2

you can’t remove protons; that would change the whole identity of the element

Valence electrons, Core electrons, and E-dot:

There are many ways to figure out how many valence electrons an atom has: 

1. Look at the periodic table   

• Elements in group 1 have 1 valence electrons,

• Elements in group 2 have 2 valence electrons,

• Elements in group 13 have 3 valence electrons,

• Elements in group 14 have 4 valence electrons, 

• Etc.

2. Calculate it

• Let’s say we want to know how many valence electrons silicon has 

• Silicon has 14 electrons

• First shell holds 2 electrons

• 2nd shell holds 8 electrons

• Then, the 3rd and last shell would have to hold 4 electrons

• Therefore, there are 4 valence electrons

• Math: 2 + 8 + x = 14; x = 4

Any electron that isn’t a valence electron is considered a core electron. 

The E-dot diagram is the diagram used to display the number of valence electrons that an element has. 

• Has the element symbol in the middle

• Starting from any side, go around the symbol and add a dot for each valence electron that the element has.

Isotopic and Mass Notation:

• Mass notation:

• Formatted like: Element - mass #

• Neon - 20 means the element is neon and it has a mass # of 20

• Carbon - 12 means the element is carbon and it has a mass # of 12

• Isotopic notation:

• Formatted like   →

• A is the mass number

• Z is the atomic number

• E is the chemical symbol

MASS # IS NOT THE SAME AS AVERAGE ATOMIC MASS.

ATOMIC MA SS # = MASS #

Average Atomic Mass calculation:

(Abundance % first atomic mass) + (Abundance % second atomic mass) + … = Average atomic mass

REMEMBER TO CONVERT PERCENTAGES INTO DECIMALS

EX: 90.48% = 0.9048         0.27% = 0.0027 

Example: 

Neon

Calculation:

(90.51% 20) + (0.27% 21) + (9.22% * 22) = Refer to last page

(0.9051 20) + (0.0027 21) + (0.0922 * 22) = ~20.187 for practice problems

Hz = Hertz

m = Meters

m/s = Meters per second

J= Joules

Wavelengths:

Electromagnetic spectrum =  the different types of lights that emit electromagnetic radiation, each one has a different frequency and wavelength. 

(Really Red Martians Invade Venus Using X-ray Guns)

Visible Light = ROYGBIV (Red, Orange, Yellow, Green, Blue, Indigo, Violet), these are the only electromagnetic waves that we can see. Red has the least amount of energy, while Violet has the most.

Atomic Emission Spectra = Unique patterns of light emitted by atoms when they are energized. There are 2 states, the ground state and excited state. 

Ground state = When electrons are at the lowest possible energy level, remember the lower the energy level, the less energy

Excited state = Ground State = When the electrons are at the lowest possible energy level, remember that the lower the energy level, the less energy there is

Excited State = Once the electrons absorb enough energy, it gets excited and goes up to a higher energy level

Emission Spectrum Lines = As the goes back to a lower energy level, it emits energy which are in the form of light (these light waves form the atomic emission spectra) 

Wavelength = the distance between two crests/troughs also could be thought of as the distance between each repeated part.

Frequency = the number of wavelengths through a given time/interval

Amplitude = the distance from the center of its oscillation (the line in the middle) to the crest/trough

Wavelength and frequency are inversely related.

Frequency and Energy are directly related.

^ This will probably be on the test, so make sure you know it!

c = the speed of light (measured in m/s) = (3.00*10⁸ m/s)

λ = the wavelength of the wave (measured in meters) 

𝜈 = the frequency of the wave (measured in hertz)

E = H(F)

E= energy (joules)

H = Planck's constant (6.626*10^-34) J*s

F = Frequency (Hz)

 Express, manipulate, and calculate chemical quantities using dimensional analysis and scientific notation.

• E = H(F)

• This can be rewritten as F= E/H

• Scientific Notation Examples -  300,000,000 = 3.0*10⁸

• Dimensional analysis - converting between units

Select an appropriate prefix for measuring a sample and convert it from one unit prefix to another. (Tera, Mega, Kilo, deci, centi, milli, micro, nano)

• Tera = trillion = 1,000,000,000,000 = 10¹²

• Mega = million = 1,000,000 = 10⁶

• Kilo = thousand = 1,000 = 10³

• deci = tenth = 1/10 = 10^-1

• centi = hundredth = 1/100 = 10^-2

• milli = thousandth = 1/1000 = 10^-3

• micro = millionth = 1/1,000,000 = 10^-6

• nano = billionth = 1/1,000,000,000 = 10^-9

Submultiples aren’t capitalized while multiples are(kilo being the exception) when abbreviated.

Example in Liters (in order): TL, ML, kL, dL, cL, mL, μL, and nL

Example questions:

Answers at the very bottom

1. What two Measurements are directly related to each other?

1. Wavelength and Frequency

2. Wavelength and Energy

3. Frequency and Energy

4. Planck's constant and Energy

2. What is the Standard Unit for Wavelength?

1. Hertz

2. Joules

3. Meters