Chemistry Semester 2 Exam

Unit 7-Unit 12

Reactants

Starting materials of a reaction

Products

Ending materials of a reaction

Yields

→

Heat has been added to the reaction.

^

-→

Reversible Reaction

--→

Catalyst

x

--→

Diatomic elements

Elements that exist in pair when they are not bonded to something else. Br, I, N, O, H, F, Cl,

Chemical Energy

Energy stored in the bonds of chemical compounds. Can change when a substance undergoes a phase change.

Chemical Reaction

Can be indicated by:

\-color change, precipitation (formation of a solid), energy changes (temperature changes), formation of a light, formation of a gas.

Exothermic Reaction

This type of reaction gives off energy and therefore feels hot to the touch. This is usually represented on a graph as a negative, indicating that the energy of the products is lower than that of the reactants.

Endothermic Reaction

This reaction absorbs energy and therefore feels cold to the touch. This is usually represented on a graph as a positive slope, indicating that the energy of the products is higher than that of the reactants.

Law of Conservation of Mass

The amount of mass/atoms is the same on both sides of a chemical equation.

Composition reaction

A reaction that is a combination of two things.

2 reactants and 1 product.

A + B → AB.

All reactions take place except two metals reacting and a noble gas reacting with another element.

Decomposition

A reaction that involves one compound breaking down into 2 or more products

1 reactant and 2 products

AB→ A + B

All reactions take place

Single Replacement

A reaction that takes place between 1 free element and 1 compound that react to form a new free element and a new compound.

A=metal A+BY→ AY + B

X=nonmetal X+BY→ BX+ Y

This reaction takes place when the reactant free element is more reactive than the product free element.

Remember that free elements have no subscript unless diatomic.

Double Replacement

A reaction that takes place when 2 ionic compounds form 2 new ionic compounds.

AX+BY → AY + BX

*H2CO3 → H20 + CO2

H2SO3→ H20 +SO2

Takes place if one of the following happens

1. An insoluble solid is formed

2. A gas is formed

3. A molecular substance appears/disappears

Combustion

A reaction that takes place when a hydrocarbon and oxygen react to form carbon dioxide and water.

C7H14O2→ CO2 +H2O

Neutralization

A reaction that takes place when an acid and base form a salt and water.

HX+BOH → BX+ HOH

Chemical Change

A change in which one substance is transformed into a new substance and new molecules are formed.

Physical Change

A usually reversible change in which the form of the matter is altered but is not changed into a different substance.

Chemical Energy

Energy stored in the bonds of molecules that can be released during a chemical reaction.

Phase Energy

Type of energy that is stored or released during a change in the state of matter and in the arrangement of particles Changes in this type of energy result in melting, freezing, vaporization, and condensation.

Thermal Energy

The energy that an object possesses due to the motion of its particles. It is directly proportional to the object's temperature and can be transferred through conduction, convection, and radiation.

False, composition reactions don’t occur if there are two metals reacting.

True or false: Li can react with Mg to form Li2Mg.

True

True or false: all combustion reactions occur

False: It is a decomposition reaction.

True or false: 2MgO→2Mg+ O2 is a single replacement reaction.

False: The correct reaction is O2+ Li2S--> S + Li2O

True or false: O2+ Li2S--> Li + OS

x=molar mass

1 mole= x grams

x=6.02 \* 10^23

1 mole= x particles

x= 22.4

1 mole= X liters

Stoichiometrey

Using chemical equations to solve problems

Mole Ratio

(coefficient 1/change) = (coefficient 2/change)

Limiting Reagent

The chemical that runs out first and stops the reaction from progressing

Excess Reagent

The chemical that is left over at the end of the reaction.

Molarity

Moles of a solute dissolved in a liter of solution.

Molar

(M) refers to the unit of concentration molarity, which is equal to the number of moles per liter of a solution

Solute

Particles being dissolved in a solution

Solvent

The substance the solute is dissolved in to form a solution.

Concentration

Measure of the amount of a solute that is dissolved in a given quantity of a solvent at a certain temperature.

Dilute

Lots of solvent, little solute, low concentration

Concentration

Lots of solute, little solvent, high concentration.

False: If three cups of sugar are added there will be more than one liter of solution.

True or false: If 3 cups of sugar are added to 1 liter of solvent the molarity would be equal to 3 cups of sugar/1 liter of solvent.

Molarity

moles of solute/liters of solution =

\*Molarity

grams of solute/(molar mass of the solute/liters of solution)= \*

Grams of solute

Molarity\* *Molar Mass* Liters of Solution=*

Dilution

Adding a solvent to a solution to lower the concentration.

Dilution Equation

M1\**V1=M2*V2*

Thompson

He discovered the electron and came up with the plum pudding model of the electron.

Rutherford

He conducted the gold foil experiment where alpha particles were shot at a gold foil. His conclusions were that the atom is mostly empty space and that the center of the atom is positively charged. He discovered the nucleus.

Protons

Subatomic particles with a charge of +1, a mass of 1.673 \* 10^-27, and they are located in the nucleus.

Electron

Subatomic particles with a charge of -1, a mass of 9.109 \* 10^-31, and they are located orbiting the nucleus.

Neutrons

Subatomic particles with a charge of 0, a mass of 1.675 \* 10^-27, and they are located in the nucleus.

\#of electrons

In a neutral atom # of protons is equal to what?

Atomic Number

The number of protons in an atom--found on the periodic table.

Mass Number

The sum of protons and neutrons in an element.

Nuclear symbol

Symbol of an element with the mass# on the top and the atomic # on the bottom

Isotopes

Multiple forms of the sane element that have the same atomic number but different mass numbers because they have a different number of neutrons. THey often have very similar properties

Atomic mass

This is equal to the mass number but measured in amu. THe average atomic mass is the average atomic mass of all of the isotopes of an element and is the same as the molar mass shown on the periodic table.

Natural elements

Elements 1-92

Man Made elements

Elements 93+

Radioactive Decay

Process of which a nucleus spontaneously disintegrated giving off radiation.

Nuclear Decay

Nuclear Reaction in which a nucleus is bombarded or struck by another nuclear particle in a particle accelerator.

\

Alpha particle

Beta Particle

Gamma Particle

Atomic Theory

Must explain: atomic emission spectra, chemical reactivity, and organization of the periodic table.

Bohr’s Theory

Electrons travel in circular orbits, electrons have fixed amounts of energy, ladder theory that energy levels are evenly spaced. His theory was false.

Quantum Mechanical Model

This atomic theory estimates the probable location of an electron and states that energy levels are not evenly spaced but grow closer farther from the nucleus.

(n) Principal Quantum Number

Quantum Mechanical Model # that describes the energy of an electron and the most probable distance of the electron from the nucleus

2 electrons

How many electrons does the first energy level hold?

8 electrons

How many electrons does the second energy level hold?

18 electrons

How many electrons does the 3rd energy level hold?

32 electrons

How many electrons does the 4th-7th energy level hold?

(l) Orbital Quantum Number

Quantum Mechanical Model # that describes the shape of the orbit.

Sphere (s)

This shape of electron orbit has 1 type, 1 orbit, and holds 2 electrons.

Dumbell (p)

This shape of electron orbit has 3 types, 3 orbits, and holds 6 electrons.

Clover (d)

This shape of electron orbit has 5 types, 5 orbits, and holds 10 electrons.

Undefined (f)

This shape of electron orbit has 7 types, 7 orbits, and holds 14 electrons.

(ml) Magnetic Quantum Number

Quantum Mechanical Model # that describes the electron’s position in space on the x, y, and z axis.

S

ml Sphere

py, px, and pz

ml Dumbell

dxy, dxz, dyz, dx2y2, dz2

ml Clover

(ms) Spin Quantum Number

Quantum Mechanical Model # that describes the electron’s spin: up for clockwise, down for counterclockwise.

Light Wave Theory

Light are electromagnetic waves and white lights is all the light in the visible spectrum.

Light Particle Theory

All matter will absorb or release energy and light is particle of energy called photons.

Photon

Particle of light energy

Inverse relationship

Wavelength to frequency relationship

Wavelength to energy relationship

Direct Relationship

Frequency to energy relationship

Atomic Emissions Spectra

Electrons absorb energy and jump to a higher energy level. Electrons lose energy and return to ground state giving off photons/light. The color of light depends on the identity of the element and the energy level of the electron.

3 truths:

\-electrons absorb and released particles of energy as they move up and down energy levels

\-they absorb only particles of a specific frequency

\-they release photons with specific frequency

Electron Configurations

Notations for elements that give the location and # of electrons around the nucleus.

True

True or false: electron configuration follows this pattern:

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p

John Newlands

He discovered the law of octaves which states that elements in a row have similar chemical and physical properties and these properties repeat every 8 elements.

Law of octaves

Elements when arranged in a row have similar chemical and physical properties and that repeat every 8 elements.

Dimitri Mendeleev

He made the first periodic table but is was arranged in order of increasing atomic mass.

Mosley

He made the modern periodic table that is arranged in order of increasing atomic number .

Periodic Law

When elements are arranged according to their atomic #s elements with similar properties appear at regular intervals.

Valence Electrons

S and P electrons that are found in the outermost shell of an atom. They determine the atom’s chemical properties and are the only electrons involved in bonding. Elements in the same column have the same number of these explaining why they have similar properties.

Group

A vertical column on the periodic table, elements in this share the same number of valence electrons and therefore have similar properties.

Period

A horizontal row on the periodic table. Elements in this row share the same energy level.

Electron Shielding

When electrons in lower energy levels block the pull of the positively charged nucleus on outer electrons.