Chemistry First Semester

How do you determine the number of sig figs?

Count the number of non-zeros (integers)

Count the zeros between non-zeros

Count ending zeros after a decimal

Cross out starting zeros

How many sig figs are in: 0.0120 m

3 sig figs (cross out starting zeros, add non-zeros and ending zero)

How many sig figs? 100.5 mL

4 (count non-zeros and middle zeros)

How many sig figs? 101

3- two non-zeros and one middle zero

How many sig figs? 350

2- two non-zeros, one eliminated ending zero

Round 5,487,129 m to 3 sig figs

5,490,000

0.013479265 mL to 6 sig figs

0.0134793

31,947.972 cm² to 4 sig figs

31,950.

What is a mixture?

Two or more elements/compounds that can be separated physically

What is a compound?

Two or more elements chemically bonded

What is an element?

One or more atoms of the same type bonded together

macrosopic

observable

submicroscopic

molecular

symbolic

representational

molecules

made from more than one atom

homogenous

appear uniform

heterogenous

can be separated easily, clear separation

Pure substance

element or compound, separated by chemical means

Physical properties

determined witthout changing the chemical structure

chemical properties

measured by changing the chemical makeup

Physical change

physical properties may change, but chemical ones don’t

Chemical change

New physical and chemical properties. New substance and composition

Intesive properties

Do not depend on the amount of matter ex:tempeerrature, boiling point, conncentration, luster

Extensive

Depends on the amount of matter Ex:weight, length, volume, entropy

Density

Mass per amount of volume

How is density different in the states of matter?

Solids are the most dense, gases are the least, liquids in the middle

accuracy

how close to actual value

precision

how close measurements are to each other

How do you use sig figs when calculating?

Round to the amount of sig figs that is lower. Ex: 25×274= 6850 25 has 2 sig figs and 274 has 3, so 6850 is rounded to 6800

How are estimates used?

Take the measurement round to the smallest unit exactly measured. Then, estimate the next digit. Ex: If water is filled between 25mL and 26mL, round to the nearest tenth for the amount, 25.6mL

what do flat lines represent on heating curves

phase changes (ex: melting)

what do slanted lines represnt on a heating curve

states of matter (ex: solid)

triple point

where all states of matter exist in unison

critical point

where a material is indistinguisable between a gas and liquid

Temperautre

The measure of average kinetic energy

Kinetic energy

collisions of particles

Heat

the flow of thermal energy between objects. Caused by differences in temperature. Flows to create equilibrium

Exothermic

releases heat

Endothermic

absorbs heat

Energy

capacity to do work or produce heat

Does adding heat always increase temp?

No, at a certain point, is it used to change phases

Specific Heat

the amount of energy it takes to heat 1g by 1°C

Lower specific heat acts how on a graph?

It is steeper because it takes less heat to increase the temperature

Higher specific heat acts how on a graph?

It is less steep because it requires more heat to change the temperature

Are specific heats the same across states of matter?

No, water, ice, and water vapor all have different specific heats

What is the specific heat formula? (Changing temperature)

q=mc∆T (energy= mass x temperature change x specific heat)

What is the phase change formula?

Q= mHvap or q=mHfus (vap is for vaporization/condensation, fus is for freezing/melting)

What does phase depend on?

Temperature and pressure

How do atrractive forces between particles vary in the phases?

Solid has the highest, then liquid, then gas. Strong is harder to separate

What is Kinetic Molecular Theory?

Molecules and particles that bounce of the wall of a container create pressure and the average kinetic energy is the temperature in Kelvin

What are teh 5 basic gas laws?

Ideal, Charles’, Boyle’s, Gay-Lussac’s, and Avogadro’s. Combined they create Combined Gas Law

What si the ideal gas law?

PV=nRT. It is used when there is no change in the system but a measurment is unknown

What is Boyle’s Law

P1V1=P2V2 V↑P↓, T is constant. Inverse relationship

What is Charles’ Law?

V1/T1=V2/T2 T↑V↑, P is constant, direct relationship

What is Gay-Lussac’s Law?

P1/T1=P2/T2 T↑P↑, V is constant, direct relationship

What is Avogadro’s Law

V1/n1=V2/n2, n↑V↑, T and P are constant, direct relationship

What is Combined Gas Law?

P1V1/T1=P2V2/T2

Democritus

Greek Philosopher who hypothesized about atoms but was not considered a scientist because he did not experiment

John Dalton

Atomic Theory. Elements are made of indivisible atoms

J.J. Thompson

Cathode Ray. Discovered electrons and that like charges repel. Plum pudding model

Ernest Rutherford

Gold foil experiment. Discovered nucleus, a positively charged, dense core in the middle. Model with ovals or model with dotted line circle

Robert Millikan

Oil drop experiment. Charge and mass of a single electron/different amounts of electrons in each element/ion

Niels Bohr

Electron Energy Levels. Electrons “jump” between levels. Planetary model

Erwin Schrödiger

Electrons move in waves, not paths. Clouds of probability

Dalton’s model

plum pudding

Thomson’s model

Rutherford one “generic/movie atom”

Rutherford’s model

Bohr’s model

Schrödiger’s model

What indetifies an atom?

Proton number and atomic number (same thing)

Where are protons located?

The Nucelus

What makes up the atomic mass?

The average atomic mass of the naturally occuring isotopes, but what makes those is the number of protons+number of neutrons

Where are electrons located?

The electron shells that orbit the nucleus

What are ions?

Charged atoms, they gained or lost electrons

What are cations?

Positive ions that lost electrons

What are anions?

Negative ions that gained electrons

What are isotopes?

Atoms that gained or lost neutrons, changes the atomic mass

what does 14 represent in “ N₇¹⁴ “

mass number

what does 7 represent in “ N₇¹⁴ “

atomic number ( # of protons)

What is average atomic mass?

On periodic table, weighted avergae of the isotope masses

What is isotope mass?

Added masses (both equal 1) of the protons and the neutrons

How do you calculate avergae atomic mass?

(mass of isotope x percentage of abundance) + (mass of isotope x percentage of abundance) added with all isotopes

What is an orbital?

Space in an atom where an electron is likely to be

What are orbital diagrams?

sublevels shown in boxes

What is electron configuration?

Condesned representation

ground state

The lowest energy state of an atom or molecule.

excited state

A state of an atom or molecule where one or more electrons have moved to a higher energy level than their ground state.

Aufbau Principle

Lowest to highest level

Hund’s Rule

Fill each sublevel singly before pairing up

Pauli Exclusion Principle

Each orbital can only hold two electrons, and they must have opposite spins.

Noble Gas Configuration

List the noble gas before the element in brackets, then continue with the electron configuration

What is light?

A form of energy that acts as both a wave and a particle

What are characteristics of waves with shorter wavelengths?

More energy, higher frequency

What are characteritics of longer wavelengths?

Less energy, lower frequency

How is color a thing?

Within the visible light spectrum, the different colors have different wavelengths, therfore have different energies, frequencies, and speeds.

Diffraction Grating

Tiny film with grooves that bends light into different colors.

Line emission spectrum

Lines created by an element’s light emission going through diffraction grating, can indentify an elemtent or the element in a compound/molecule