AP Chem Unit 1 Test Key Ideas from notes

Average mass

_______ stays the same no matter how big the sample is

2 molecules with the same atoms but in different ratios will:

have different average masses

Mass %

How much of the mass of the compound is made up by each different atom within the compound

Empirical Formula:

simplest chemical formula

Coefficients in a chem. equation represent

represent the moles in the chemical equation

The mole is a the bridge between the number of ________ in an object and the _____ of an object

particles; mass

What do you use avagadro’s number for?

To find the number molecules of a substance in a given mass

What does avagadro’s number represent?

the number of molecules per gram of a substance

Ionization energy

amount of energy needed to create an ion(to lose or gain an electron)

Coloumb’s Law:

opposites attract, same charges repel and the closer they get, the bigger the charge; the closer an electron is to the nucleus, the stronger its attraction is to the nucleus(stronger the force between it and the nucleus)

Photoelectric effect

If you hit matter with photons/light, it will eject electrons

Photoelectron Spectroscopy in simple terms:

hitting matter with light and measuring the electrons that come out

Valence electrons:

electrons in the outermost shell

Core electrons

electrons in the inner most shell

Core electrons _____ valence electrons from the _____ to the nucleus

shield valence electrons; from the attraction

Atoms with ______ protons/_____ charge have a higher ionization energy, as they have a stronger pull on their electrons from the ______ amount of protons/_____ charge on the inside

more protons/positive charge; higher amount of/positive

Electrons _____ throughout a sublevel’s orbitals before they are forced to pair up

spread out throughout a sublevel

What happens when there is one pair of electrons in 1 orbital in the valence shell?(first pair of electrons in outer shell)

There is a drop in ionization energy as this pair of electrons creates repulsion between the pair, decreasing attraction

As you increase the size of an atom, you ______ the number of protons, and therefore make it _________ to pull an electron away

increase the number of protons; make it harder

First ionization energy ______ as you move Left to right across the periodic table(increasing protons)

First ionization energy increases

first ionization energy ______ going up to down on the periodic table(increasing radius, same number of valence)

First ionization energy decreases

Overall, first ionization energy ______ as you move up and to the right

overall, first ionization energy increases

As you increase atomic number, you _____ the # of protons, which _____ the electrons ______ closely in

increase the #; which pulls; more

Atomic and ionic radii ____ as you move top to bottom on the table

atomic and ionic radii increase

Atomic and ionic radii ______ as you move left to right across the table

atomic and ionic radii decrease

Electronegativity _____ as you move left to right across the periodic table(think increase in protons and positive charge + what is electronegativity?)

electronegativity increases

electronegativity _____ as you move top to bottom on the periodic table

electronegativity Increases

electronegativity and ______ energy follow the same periodic trends

and ionization energy

How do you determine typical ionic charge based on the periodic table?

Look at how many electrons need to be lost/gained to become a noble gas and is it easier to gain or lose an electron based on where the element is on the table

What is an orbital?

Where electrons spend most of their time as electrons don’t follow specific orbits

What are the orbital shapes and how many orientations each has?

s(1), p(3), d(5), f(7)

How many electrons fit in 1 orbital(based on spin)?

2 electrons

To find the number of electrons per orbital shape you take the number of electrons in 1 ____(how many can it have based on the spin rule?) multiply it by the number of ______ the shape has

electrons in one orbital; # of orientations the shape has

Isotopes are

The same element with a different mass

Step 1 of a mass spectrometer(what charge does it create?)

Hit a sample with electrons to move them through the sample and pull electrons away from the sample. this creates a positive charge as it ionizes the sample.

Step 2 of a mass spec.

A magnet bends the path of the ions(like driving around a curve) to sort them by mass. Slower ions have a harder time getting around the curve while lighter ions can go closer to the curve.

Step 3 of mass spec.

electron multiplier, which is a plate that when hit by electrons, spawns more electrons, creating a signal that is then amplified by an amplifier

Why do we calibrate a mass spec.?

To start sending ions through the machine to determine how strong the magnet needs to be in order to properly sort the ions based on mass

Average atomic mass(aka. atomic weight) equation

atomic weight = (mass of isotope)(abundance of isotope) +(mass of isotope)(abundance of isotope) + etc.

Light is a wave AND a _____

AND a particle

A high frequency light wave =

high energy wave

Beer-Lambert’s Law

the higher the concentration of the solution, the less light goes through it

What is a limiting reactant?

A substance we don’t have enough of so it limits the amount of product that can be made in a reaction

How do you identify the limiting reactant?

Calculate the amount of a product that would be formed using the given amount of mass of each reactant. The reactant that produces the least product is the limiting reactant, and gives the actual amount of product you would produce

Percent Yield Equation

actual yield of product/theoretical yeild of product * 100

Gas Law states:

1 mole of a gas is 22.4 liters of that gas

equation for expected product:

grams * moles* moles * grams

equation for molar masses of gases

liters * moles moles * liters

Where is the equivalence point on a titration curve?

When there is a straight line up

equation for titration

liters of solution needed to reach equivalence moles * moles * liters

Gravimetric analysis general equation:

precipitate mass —> precipitate mass —> analyte(what you’re looking for)moles —> analyte mass

Steps for finding net ionic equation from a given reaction

1. equation for reaction

2. Balance the equation and add states of elements

3. Break apart all non solid elements into their ions

4. If looking for net ionic, cross out compounds in the same state found on both sides of the equation

Synthesis Reaction:

taking atoms or molecules, and combining them to make a new compound

Decomposition reaction

breaking a compound into atoms or molecules

A hydrogen ion is the same as

a proton

Acids _____ to bases, and bases _____ electrons

donate to bases; accept electrons

Conjugate base and acid

new base/acid formed on the right side of the equation from the original base/acid, that can react again to form the original base/acid