Chemistry 4thQ

Chemistry Reviewer ; Mikaela Aquino

Phases of Matter

• solid

• liquid

• gas

• plasma

• Bose-Einstein condensate

• quark-gluon plasma

• degenerate matter

Phase Changes

Melting - solid to liquid

Freezing - liquid to solid

Evaporation - liquid to gas

Condensation - gas to liquid

Sublimation - solid to gas

Deposition - gas to solid

Specific Latent Heat

What is SLH?

The SLH of a substance is the amount of energy required to change the state of 1kg of the substance with no change in temperature.

SLH of Fusion

solid to liquid or vice versa

SLH of Vaporization

liquid to gas or vice versa

♡ The temperature is constant during these times.

• The energy of the system is breaking apart/weakening or creating bonds between the particles.

Formula

E = m(L)

L = E/m

m = E/l

E = energy for a change of state (J/Joules)

m = mass

L = specific latent heat (J/kg)

♡ When we heat a substance, we increase the temperature as we increase the energy of the particles. When the substance changes state, the temperature stops increasing and stays constant. Now, the energy we’re putting in is weakening or breaking the forces of attraction between the particles.

Particulate Nature of Matter

Matter - anything that has mass and takes up space.

Particles - tiny building blocks which makes up matter

1. Everything is made up of particles

Atoms - smallest particles that cannot be broken down further.

Molecules - the particles consisting of two or more atoms joined together.

Ions (Cation/Anion) - atoms or group of atoms that carry a charge.

Distinguishing Properties

Solid

• fixed shape & volume

• does not flow

• arranged in a lattice

• strong forces between particles

• vibrates in fixed position

Liquid

• shape changes (takes form of container)

• fixed volume

• flows easily

• weaker forces between particles

• particles are closer together, but not in a lattice

• can move about & slide past each other

Gas

• no fixed shape & volume

• lighter than solids and liquids

• moves about very quickly, collides with each other & bounces off in all directions

• particles are far apart

• almost no forces holding them together

Evaporation, Sublimation, Melting

• particles gain more energy

• particles move around faster which weakens the forces holding the particles together.

Condensation, Freezing

• particles won’t have enough energy to overcome forces of attraction so bonds will start to form between the particles.

Theories on Atoms

1. Matter is composed of atoms

• Matter must be composed of atoms because it is the foundation of matter.

• Matter has mass and can occupy space because it is composed of atoms

2. An atom is mostly empty space

3. Atoms exert forces of attraction and repulsion.

• opposites attract, same charges create a repulsion force.

4. Atoms move in constant-random motion, atoms possess kinetic energy

• With an increase in temp, particles move faster as they gain kinetic energy, resulting in increased collision rates and an increased rate of diffusion.

Page 204-207 of the Science Book

Atomic Structure

Atoms are what we call the particles that make up matter. The protons & neutrons are found at the center or in the nucleus. Revolving around the nucleus are the electrons.

Ions

• Atoms that are charged, either positively or negatively

• happens when there is removed or added electron in the valence shell

Types of Ions

• Anion - negative (-)

• Cation - positive (+)

Octet Rule

• the tendency of atoms to prefer to have 8 electrons in the outermost shell.

• makes it stable

• added electrons = anion

• removed electrons = cation

Formulas

Mass Number = # protons + # neutrons

Neutrons = Mass # - protons

Electrons = Atomic # - charge

Protons = Atomic #

Charge = # protons - # electrons

Quantum Mechanical Model

Aufbau principle tells us the order in which an atom will fill up its orbitals.

• fill lower orbitals before higher ones

Hund’s rule states that for electrons of the same energy, you put one electron in each orbital first before doubling them up.

• place one electron in degenerate orbitals (p, d, f) before adding a second one

Pauli exclusion principle states that no two electron can have the same four quantum number.

• electrons must have opposite spins

Quantum Numbers

• size, shape, & orientation or orbitals

• characteristics of electrons in relation to the orbitals (energy & spin)

 Principle Quantum Number

• refers to the size (n)

• size of the orbital or area where electrons can be possibly found.

• expressed in numbers

• the larger the value of n, the bigger the shell and higher the energy

Angular Momentum 

Quantum Number

• refers to the shape (l)

• shape of the orbital or area where electrons can be possibly found

• s, p, d, f

Electron Configuration

represents the arrangement of electrons distributed among the orbital shells and subshells.

If you add all the exponents, it should be equal to the atomic number.

Periodic Table of Elements

Dmitri Mendeleev

• introduced the Periodic Table of Elements

• proposed the Periodic Law

Periodic Law: “When elements are arranged in order of increasing atomic number, there is a periodic repetition of their chemical & physical properties.”

Periods

• rows in the periodic table 

• there are 7 periods

• number of energy shells in an atom

Groups

• columns in the periodic table

• there are 8 groups

• number of valence electrons in the outermost shell

Families

• columns in the periodic table

• there are 8 families

• each element in the same family also have the same characteristics

Alkali Metals - Group 1A

• does not include hydrogen

• shiny, malleable, ductile

• softer than other metals

• most reactive of all the metals

• vigorously reactive w/ water

• 1 valence electron

Alkaline Earth Metals - Group 2A

• not as reactive as Group 1A

• shiny malleable, ductile

• high thermal & electrical conductivity

• denser than the alkali metals

• higher melting points than 1A

• reactive w/ water

• 2 valence electrons

Transition Metals - Group 3-12

• shiny, malleable, ductile

• often form colorful compounds

• variable number of valence electrons

• hard metallic sounds

• higher thermal & electrical conductivity

• includes lanthanides and actinides

Boron Group - Group 3A

• aka Earth Metals

• solid at room temperature

• diverse properties, intermediate between metals and nonmetals

• 3 valence electrons

Carbon Group - Group 4A

• aka Tetrels

• can carry a charge of 4

• diverse properties, intermediate between metals & nonmetals

• 4 valence electrons

Nitrogen Group - Group 5A

• aka Pnictogens 

• diverse properties, intermediate between metals & nonmetals

• 5 valence electrons

Oxygen Group - Group 6A

• aka Chalcogens

• diverse properties, intermediate between metals & nonmetals

• 6 valence electrons

Halogens - Group 7A

• reactive nonmetals

• melting & boiling points increase with increasing atomic #

• changes state as it moves down

• high electron affinities

• 7 valence electrons

Noble Gases - Group 8A

• aka Inert Gases

• extremely unreactive

• 8 valence electrons = stable

Periodic Trends

Many properties of elements change in a predictable way as you move through the periodic table. 

• explained in terms of energy levels and the presence of electrons in the elements.

Atomic Size/Radius

• measured as one-half the distance between the nuclei of identical atoms that are bonded together

• increases from right to left

• increases from top to bottom

Ionization Energy (remove)

• energy required to remove an electron from a gaseous atom to form a cation

• increases from left to right

• increases from bottom to top

Electron Affinity (accept)

• ability of an atom to accept an electron

• metals usually have low electron affinity, while nonmetals have high electron affinity.

• increases from left to right

• increases from bottom to top

Electronegativity (attract)

• ability of an atom to attract electrons towards itself.

• when atoms of two different elements share a pair of electrons, one atom becomes partially positive and the other becomes partially negative.

• increases from left to right

• increases from bottom to top