CHEM REVIEW: 281 ways to pass the Chemistry Regents

Flashcards of key vocabulary and concepts from the Chemistry Regents Review.

Solubility

Dependent on temperature for solids (upward curve on Table G)

Table G

Use when given a temperature and asking about a salt dissolved in water (on the line is saturated, below = unsaturated, above = super)

Likes dissolve likes

Polar mixes with polar substances

Table F

Insoluble compounds will not fully dissolve in water and will be in solid phase; soluble compounds will dissolve in water and be in aq phase

Ions and BP/FP

More ions, more change in BP/FP

Adding something to water (such as a salt)

Freezing point decreases (more salt = lower the freezing point)

Adding something to water (such as a salt)

BP increases (more salt = higher BP)

PPM

(grams of solute / grams of solution) x 1,000,000

Molarity

Moles/L

Chemical Reaction Requirement

Sufficient energy and proper orientation for new bonds to form

Chemical Reaction

Need effective collisions

Increase Temperature

Increases reaction rate (more collisions)

Increase Pressure

Increases reaction rate (more collisions)

Lower Concentration

Slow reaction rate because of less collisions

Greater Surface Area

Higher rate of reaction

Activation Energy

Goes from the reactants to top of curve

Reverse Activation Energy

Goes from the products to top of the curve

Exothermic Reaction

Starts high and ends low

Heat of Reaction

Potential energy of products - potential energy of the reactants

Catalyst

Speeds up a reaction by providing a different reaction pathway that lowers the activation energy

Entropy (disorder)

Gases have the highest entropy, then liquid/aq and solids have the lowest

Nature

Undergoes changes towards higher entropy and lower energy

Safety Precaution (Long Hair)

Tie back your hair

Spilled Liquid on Arm

First rinse your arm and then tell the teacher

After Laboratory Experiment

Dispose of chemicals properly

Scientific Method

All variables must remain the same except the variable you are testing

Graphing

Make an even scale of numbers and circle final points

Atom

Contains subatomic particles (protons, neutrons, electrons) that make it divisible

Protons

+1 charge

Neutrons

0 charge

Mass of Neutron

1 amu (atomic mass unit)

Electrons

-1 and a mass of 0

Charge of electron

-1, charge of proton +1 (same magnitude, opposite charge)

TABLE O

Shows symbols, mass and charges of particles (electrons are represented as beta)

Protons and Neutrons

Located in the nucleus of an atom

Charge of an atom's nucleus

(+) number of protons

Atoms

Positively charged nucleus and negatively charged electrons located in 'clouds' (orbitals) around an atom's nucleus

Mass Number

protons + #neutrons

Atomic Number

Number of protons (All atoms of the same element have the same atomic number)

Number of Neutrons

Mass number - atomic number

Isotopes

Atoms with the same number of protons, different number of neutrons (different mass number)

Mass number

top number of isotope notation

Other notations

Number after an element represents mass number

Average Atomic mass

(isotope1 mass) (% in decimal form) + (isotope 2 mass) (% in decimal form)

Abundance

Whatever whole number the atomic mass is closest to on the Periodic Table means that isotope is most abundant

Rutherford's Gold Foil experiment

Shows an atom is mostly empty space with a small, dense, positively charged nucleus

Thomson and Bohr's models

Showed electrons present in an atom

Wave-mechanical model (electron cloud model)

Shows that an orbital (cloud) is the most probable location of electrons

Neutral Atom

An Atom has the same number of protons and electrons as long as there is no charge (total charge of 0)

Total (Net) Charge of an atom

protons - # electrons

Ion

A charged element (it has lost or gained electrons): electron configuration will change if it is an ion (possible charges are found on PT)

Electron Configuration

Shows location of electron in their shells

First shell

Less energy than 2nd shell

Valence Electrons

Electrons found in the outer most shell (last number in electron configuration)

Lewis Dot Diagram

Just shows the valence electrons (electrons represented by dots, drawn in pairs)

When excited electron moves to ground state

A specific amount of energy is emitted (sometimes as light/bright line spectrum)

Excited electron configuration

Is not the same as the configuration on the reference table (there will be one less electron in one energy level and one more electron in another energy level)

When viewing a Bright line spectrum

Elements must line up exactly to be part of the mixture in the spectrum

Positron and beta particles

Same mass (0) & opposite charge (Beta negative, positron positive)

Beta Particle

Less mass and greater penetrating power than a +alpha particleGamma radiation has the greatest penetrating power

Nuclear Reactions

All Nuclear reactions are transmutations (examples: fission, fusion, decays)

Any element after Po

Naturally unstable and will spontaneously decay

Decay modes and half lives on table N

Show alpha, beta, positron decay

Natural Transmutations

Spontaneous radioactive decay = 1 reactant → 2 products (elements must change)

Nuclear Decays

Release the decay particle

Completing nuclear equations

Add up mass number and atomic numbers on each side of the arrow (must be equal on both sides)

Fusion

Light nuclei combine to form a heavy nucleus and a lot of energy (energy is sometimes in the form of a neutron)

Fusion

Releases more energy than fission

Nuclear reactions (such as fission or fusion)

Releases more energy than a chemical reaction (redox, substitution, neutralization)

Nuclear reactions

Mass is converted into energy

Half life

The length of time it takes for ½ mass of a sample to decay

Radioisotopes are used for dating of

Geological formations (C-14)

I-131 used to diagnose

Thyroid disorders

Radioisotopes can

Treat cancer but can also cause mutations in healthy cells (Co-60)

Substance

Compound or element

Elements

Cannot be broken down by chemical means (it is an element if it is on the Periodic table/Table T)

Compounds

Can be broken down by chemical means

Same compound

Same chemical property, different compound = different chemical properties

7 diatomics

BrINCIHOF (Br2,12, N2, Cl2, H2, O2, F2)

Liquid at a specific temperature

MP Specific Temperature <BP

Mixture

Can vary in proportion of its components (example: Salt water)

Homogeneous mixtures (solutions)

Even distribution of particles (aq-dissolved in water) substance has to be soluble to mix with water

Heterogeneous mixtures

Not even throughout. Contains a substance that will not be soluble in water.

When substances are mixed

They retain their properties

Mixtures that contain substances with different density and particle size

Can be separated by physical means

Distillation

Separates liquids with different boiling points (water and alcohol)

Chromatography

Method of separating particles by solubility and polarity

Evaporation

Separates a salt dissolved in water

Chemical Property

How substances react

Chemical Change

Results in the formation of a difference substance (example: burning)

Physical Change

Do not form new compounds, commonly phase changes (change in distance between molecules)

Solids

Atoms close together, liquid in the middle, gas = atoms far apart

Deposition

Gas to solid phase change

Sublimation

Solid→Gas phase change (ex: CO2)

In a phase change diagram

The flat parts represent the phase changes (Potential Energy [PE] changes and Kinetic Energy [KE] remains the same)

In a phase change diagram

The sloped lines represent heating or cooling (PE remains the same and KE changes)

Density

mass/volume (g/L or g/cm³)

Higher density

Sinks to bottom of tank

Density

Never changes for each element

Sig Figs: Atlantic pacific

Decimal absent, count from the first nonzero number on the Atlantic side/right and count all numbers to the left; decimal present, count from the first nonzero number on the pacific side/left and count all number to the right