​Barsam's Chemistry Reteach and Explanations

​Barsam's Chemistry Reteach and Explanations

By Chelsea McBride

​Making Measurements w Sig Figs

​Be sure to read all of the digits (numbers) from the measuring device and then estimate one digit (number)!

​Determining the number of sig figs in a measurement . . .

​Use your "zero" rules!

• ​Nonzero digits always significant!

• ​In between zeros always significant!

• ​Trailing zeros only significant when a decimal point is present!

• ​Leading zeros are never significant!

​Determining the number of sig figs in a measurement . . .

​Use your Atlantic-Pacific Rule!

​Calculations with Sig Figs

​Know your rules for adding/subtracting and multiplying/dividing!

​Calculations with Sig Figs

​Know your rules for adding/subtracting and multiplying/dividing!

​Density Calculations

​The formula for calculating density is on Reference Table T!

Unit Conversion

Sample Lesson

What are conversion factors?

• You just found some...

• A number used to change one set of units to another, by multiplying or dividing

  • equivalent values measured in two different units

How many eggs are in 5.5 dozen?

'mental math' tricks --> 66 eggs

5.5 dozen x 12 eggs = 66 eggs
1 dozen

Factor-Label Method
(Dimensional Analysis)

1. Start with the unit you know...and figure out where you're trying to go

Factor-Label Method
(Dimensional Analysis)

1. Start with the unit you know...and figure out where you're trying to go

5.5 dozen eggs = ?? eggs

​Know: Go:

Factor-Label Method
(Dimensional Analysis)

1. Start with the unit you know...and figure out where you're trying to go

2. Use conversion factors to change units

5.5 dozen eggs = ?? eggs

Factor-Label Method
(Dimensional Analysis)

1. Start with the unit you know...and figure out where you're trying to go

2. Use conversion factors to change units

1 dozen eggs = 12 eggs, so....

5.5 dozen eggs 12 eggs = ?? eggs
1 dozen eggs

​x _______

Factor-Label Method
(Dimensional Analysis)

1. Start with the unit you know...and figure out where you're trying to go

2. Use conversion factors to change units

3. Solve (multiply everything on the top and divide by everything on the bottom)

5.5 dozen eggs 12 eggs = ?? eggs
1 dozen eggs

x _______

Factor-Label Method
(Dimensional Analysis)

1. Start with the unit you know...and figure out where you're trying to go

2. Use conversion factors to change units

3. Solve (multiply everything on the top and divide by everything on the bottom)

5.5 x 12 / 1 = 66 eggs

5.5 dozen eggs 12 eggs = ?? eggs
1 dozen eggs

x _______

​/ / / /

​/ / / /

What if it takes more than one step/conversion?

Just add more conversion factors!

How many inches are in 3 miles?

How many inches are in 3 miles?

Know: Go:
3 miles = ?? inches

Conversion factors: 12 inches = 1 foot and 5280 feet = 1 mile
Solve:

How many inches are in 3 miles?

Know: Go:
3 miles = ?? inches

Conversion factors: 12 inches = 1 foot and 5280 feet = 1 mile
Solve:
3 miles 5280 feet 12 inches = ?? inches
1 mile 1 foot

​x ______ x ______



= 3 x 5280 / 1 x 12 / 1 = 190,080 inches!

Metric Conversions

(The rest of the world's system measuring system)

Isotopes, Ions and Average Atomic Mass

By TROB

ISOTOPES:

• Same Element

• Different Mass Number

• WHICH MEANS DIFFERENT # of NEUTRONS

What does changing # of Neutrons do?

• Neutrons make atoms stable

• Unstable = Wants to fall apart

• Fall Apart = Split into smaller atoms

• Split Apart = RADIOACTIVE

What decay of Uranium - 238 looks like.

Average Atomic Mass

• DIFFERENT than Mass Number

• Average of all of the isotopes of an atom found in nature.

How they get that number

• % abundance of that isotope x actual mass of that isotope

• add together

• divide by 100 (if you didn't put into percentage first)

How to tell which isotope is more abundant?

• CLOSEST TO ROUNDED AVERAGE ATOMIC MASS

• So the most abundant isotope of Gold would be?

• Gold - 197

Ions

• Ion means charged atom

• To be charged it needs more or less electrons than protons

• more electrons = NEGATIVE

• less electrons = POSITIVE

Ion Notation

• Same as isotope

• includes charge in upper right

• + means LESS ELECTRONS than PROTONS

• (-) means MORE ELECTRONS than PROTONS

Density

Grams to particles and particles to grams

How do I convert molecules/particles/atoms to grams or vice versa? You can use this --> diagram to help you.

Grams to molecules is the same thing as saying grams to atoms or particles.

Molar Mass

Counting Atoms

Molar Mass

• The molar mass, also known as molecular weight, is the sum of the total mass in grams of all the atoms that make up a mole of a particular molecule.

• Measured in the unit: grams/mole

How to Calculate Molar Mass

• 1. Count How many atoms you have of each element.

• 2. Find the atomic mass of each element and multiply it by their number of atoms.

• 3. Add up all the masses.

Molecular Formulas

By K. Witt

Light and Quantized Energy

by Jennifer Haycraft

​Properties of Light

Electromagnetic Radiation​ is a form of energy that exhibits wave-like behavior as it travels through space.

​

​The wave consists of electric and magnetic fields that vibrate and create waves.

​Electromagnetic Radiation

Gamma Rays, X-rays, Ultraviolet, Visible Light, Infrared, ​Microwaves, and Radio Waves are all types of EMR.

​ROYGBIV

​Represents red, orange, yellow, green, blue, indigo, and violet and is the visible spectrum. Red waves have the lowest energy, the longest wavelength, and lowest frequency. Violet waves have the highest energy, shortest wavelength, and highest frequency.

​Properties of Waves

​Speed of Light

• ​Wavelength and frequency are inversely proportional.

• ​Frequency and energy are directly proportional

• ​How are wavelength and energy related?

Chem04 Quantum Shells, Subshells, Orbitals

by Nicholas Hendley

​Loosely adapted from Chemistry: Concepts and Problems

​Quantum Numbers define the Electron

​Every electron is defined by FOUR quantum numbers.

• ​The Principal Quantum number (n) describes the energy level (shell).

• ​ ​The Angular Momentum (or Azimuthal) Quantum number (l) describes the energy sublevel (subshell).​ [Sometimes, this is called the orbital shape, but it is a sublevel.]

• The Magnetic Quantum number (m_l) describes the orbital (orientation).​

• The Spin Quantum number (m_s) describes the electron.

​The Principal Quantum Number (n)

​Corresponds to the energy level (or energy shell).

​Possible values of n = 1, 2, 3, 4, 5, 6, 7

​The lowest energy is n = 1.

​The highest energy is n = 7.

​

​The Angular Momentum Quantum number (l)

​Corresponds to the energy sublevel (or energy subshell).

​Possible values of l = 0 up to n - 1

​This defines the shape of the orbitals.

​Four Sublevel Shapes

​l = 0 = s

"sphere"

​​l = 1 = p

"peanut" or "dumbbell"

​​l = 2 = d

"double dumbbell"

​​l = 3 = f

"flower"

​Assigning Electrons

• ​Imagine this is like an apartment building.

• ​The first energy level (n = 1), can only support an s sublevel.

• ​The second energy level (n = 2), can support only 2 sublevels: s and p.

• ​The third energy level (n = 3), can support only 3 sublevels: s, p and d.

• ​The fourth energy level (n = 4), can support all 4 sublevel types: s, p, d and f.

​Naming sublevels

Naming the sublevels by using the energy level, then the sublevel shape.​

• ​So, the s sublevel on n = 1 would be called 1s.

• ​​Next would be the s sublevel on n = 2 would be called 2s.

• ​The p sublevel on n = 2 would be called 2p.

• And so forth.

​Magnetic Quantum Number (m_l)

​​Corresponds to the orbital.

​Possible values range from -l to +l, including 0

Each orbital can only hold 2 electrons

​Orbitals per sublevel

​An s (l = 0) sublevel has 1 orbital

(m_l = 0)

​​A p (l = 1) sublevel has 3 orbitals

(m_l = -1, 0, +1)

​​A d (l = 2) sublevel has 5 orbitals

(m_l = -2, -1, 0, +1, +2)

​​An f (l = 3) sublevel has 7 orbitals

(m_l = -3, -2, -1, 0, +1, +2, +3)

​

​In the apartment analogy, these are like the rooms of the apartments.

​The Spin Quantum Number (m_s)

​​​Corresponds to the electron.

​Possible values are either +½ or -½

Each orbital can only hold 2 electrons

​Electrons must have opposite spins within the same orbital

​Periodic Trends

Introduction to Ions

Ms. Sylvia

Ion

• Charged atom that has lost or gained an electron

• There are two different types of ions

Cations

• These are atoms that give up electrons

• The elements that give up electrons are METALS

• When a metal gives up an electron, it becomes positive

Anions

• These are atoms that take in electrons

• The elements that take in electrons are NONMETALS

• When a nonmetal takes in an electron, it becomes negative

Why Atoms Lose or Gain Electrons

• To have a noble gas electron configuration

• For example, when lithium loses an electron, it will have the same number of electrons as helium.

• For example, when fluorine gains an electron, it will have the same number of electrons as neon.

Main Points

• Ions = charged atoms that lost or gained an electron

• Cations are atoms that lost an electron

• Cations can only be metals

• Anions are atoms that gained an electron

• Anions can only be nonmetals

Group Names

• Group 1 = Alkali Metals

• Group 2 = Alkaline Earth Metals

• Groups 3-12 = Transition Metals

• Group 17= Halogens

• Group 18= Noble Gases

Electron Configuration Practice

The Periodic Table

-Divided into different sections

-Helps to identify the energy levels of the elements

How to Write an Electron Configuration:

1. Start with the shell/period number

2. Followed by the type of orbital

3. Finally the superscript indicates the number of electrons in the orbital

Example: B = 1s² 2s² 2p¹

Electron Configuration Practice

Assigning Oxidation Numbers

Bromfield Honors Chemistry

Rule #1

​Uncombined elements

Uncombined elements have an oxidation number of 0.

Rule #2

​Monatomic ions

The charge of a monatomic ion is its oxidation number​

Monatomic ions: examples

Li⁺ oxidation # = +1

​

N^3- oxidation # = -3

​

Fe²⁺ oxidation # = +2​

​

Cl- oxidation # = -1

Rule #3

​F in compounds

In compounds, the oxidation number of F is -1.

Rule #4

​H in compounds

Hydrogen atoms in a compound almost always have an oxidation number of +1

Rule #4, continued

​Metal hydrides

In metal hydrides, the oxidation number of H is -1

Rule #5

​Oxygen in a compound

Oxygen in a compound usually has an oxidation number of -2.

Rule #5, continued

​Oxygen in peroxides

In a peroxide, oxygen atoms have an oxidation number of -1.​

Rule #5, continued

​O in compounds with F

In a compound with F, O has an oxidation number of +2

Rule #6

​Neutral compounds

In a neutral compound, the sum of the oxidation numbers is 0.

Rule #7

​Polyatomic ions

In a polyatomic ion, the sum of the oxidation numbers equals the overall charge of the ion.​

The Periodic Table

-Divided into different sections

-Helps to identify the energy levels of the elements

How to Write an Electron Configuration:

1. Start with the shell/period number

2. Followed by the type of orbital

3. Finally the superscript indicates the number of electrons in the orbital

Example: B = 1s² 2s² 2p¹

Expanded Periodic Table

How the f block fits into the periodic table with the other energy levels

Read the energy levels from left to right, top to bottom

Hydrogen (1s¹)

-The first element on the periodic table

-The element that starts the electron configuration levels

-1 electron on the inner most shell

Helium (1s²)

-The second element in period 1

-2 electrons on the inner most shell

-Start at H and move across the period to count the valence electrons

Beryllium (Be)

-The second element in period 2

-2 electrons on the second shell

-Start at H and move across the period to count the valence electrons

-Move down a period and count across, stopping at Be

Chlorine (Cl)

-The seventh element in period 3

-7 electrons on the third shell

-Start at H and move across the period to count the valence electrons

-Move down a period and count across

-Repeat, stopping at Cl

Nickel (Ni)

-The tenth element in period 4

-8 electrons in 3s & 3p + 8 electrons in 3d block

-2 electrons on the fourth shell

-Start at H and move across the period to count the valence electrons

-Move down a period and count across

-Repeat, stopping at Ni

Krypton (Kr)

-The eighteenth element in period 4

-8 electrons in 3s & 3p + 8 electrons in 3d block

-8 electrons on the fourth shell (2 in 4s & 6 in 4p)

-Start at H and move across the period to count the valence electrons

-Move down a period and count across

-Repeat, stopping at Kr

Terbium (Tb)

-The eleventh element in period 6

-18 electrons in 4s, 4p, & 4d + 9 electrons in 4f block

-8 electrons in 5s & 5p

-2 electrons in the sixth shell

-Start at H and move across the period to count the valence electrons

-Move down a period and count across

-Repeat, stopping at Tb

Introduction to

Naming IONIC Chemical Compounds

​Metal names will always GO FIRST

• Metal names STAY THE SAME

​Non-metals

• Non-metals get a name change when they bond with Metals.

​Non-metals

• Non-metals name will change with a new -IDE ending

​Non-metals --> Bonded Anions

• Hydrogen --> HydrIDE

• Carbon --> CarbIDE

• ​Nitrogen --> NitrIDE

• ​Oxygen --> OxIDE

• ​Fluorine --> FluorIDE

• ​Phosphorus --> PhosphIDE

• ​Sulfur --> SulfIDE

• ​Chlorine --> ChlorIDE

• ​Selenium --> SelenIDE

• ​Bromine --> BromIDE

• ​Iodine -> IodIDE

• Non-metals will always be ​LISTED LAST

​Metal FIRST --> Non-Metal LAST + IDE

• Example: Table Salt

​

• NaCl = Chemical FORMULA

​

​Metal FIRST --> Non-Metal LAST + IDE

• Example: Table Salt

​

• NaCl = Chemical FORMULA

​

​Sodium ChlorIDE = Chemical NAME

Molecular Structures & Electronegativity

Good Things!

The further "right" an element is, the more electronegative is.

Naming acids