Chem Final First Semester

Atom

The smallest unit that makes up all matter

Subatomic particles

make up an atom

AMU

atomic mass unit (size)

Atomic Mass

A weighted average mass for an element including all known isotopes

Mass Number Equation

mass # = # of protons + # of neutrons

Atomic Number

number of protons

Molecules

two or more atoms bonded together

Energy

the capacity to move or change matter

Kinetic Energy

energy due to motion

Thermal Energy

the total kinetic energy of all of the particles that make up matter

Potential Energy

stored energy due to the position relative to the matter

Chemical energy

potential energy stored in chemical bonds that hold atoms together

System

the portion of the universe that a scientist identifies for study

Surroundings

everything else around the system

Isotopes

Atoms that have the same number of protons but different numbers of neutronsAtom Emission Spectrum

Energy Levels

The fixed energies an electron can have

Quantum of Energy

The amount of energy required to move an electron from one energy level to another

Quantized Energy

Electrons must absorb or give off a certain amount of energy to move between energy levels

Ground State

The lowest possible energy level

Excited State

The electron has gained energy and is in a higher energy level

Emission Spectrum Line

Each spectral line has a specific wavelength and is for one electron transition to a lower energy level

Quantum Mechanical Model

does not specify an exact path for electrons moving around the nucleus but instead defines a region of space where there is a high probability of finding an element

Shell Model

A simplified version of the quantum mechanical model where each principal energy level has a different number of subshells

Atomic orbital letters

s, p, d, and f

Where do electrons populate first (subshells)?

They populate the lowest possible energy subshells first

Subshells in order

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

Electron Configurations

The ways in which electrons are arranged in various orbitals around the nuclei of atoms

When do electrons pair (subshells)?

Only after each subshell is half full.

Spin

A property of electrons that may be thought of as clockwise or counterclockwise orientation

Stability

Atoms are more stable when the electrons are in the lowest energy orbitals

How do unstable arrangements become stable?

They lose energy

What can you use the periods on the periodic table for in subshells?

The period number is the value of the principal energy shell

What two elements have abnormal electron configurations?

Chromium (Cr) and Copper (Cu)

Valence Electrons

Electrons in the outermost energy shell

What stands out about the electrons in noble gases?

The subshells in the valence shell are full

Electron Dot Structures

Simple diagrams that show the number of valence electrons, represented as dots around the element symbolDöbereiner

Newland

1865 Octaves; every eighth element had similar properties to the first

Mendeleev

1869-1871 Predicted existence of undiscovered elements based on gaps in the patterns of properties; organized elements in octaves in mostly order of atomic mass

Period

Horizontal row of elements

Group

Vertical column of elements that have similar physical and chemical properties

Metals

80% of elements

Solid at room temperature

Good conductor of heat and electricity

Malleable

Ductile

Have luster

Metalloid

Solid at room temperature

No luster

Poor or semi conductor of heat and electricity

Can be changed by using mixtures

Malleable

Can be shaped into different physical forms

Ductile

Can be pulled and stretched into wires

Nonmetal

Brittle

Poor conductor of heat and electricity

Not ductile or malleable

Can be all three states of matter at room temperature

Main group elements

Elements in groups 1 and 2 and 13-18

Noble gases

In group 18

Relatively non reactive

Alkali metals

In group 1

Very reactive

Alkali Earth Metals

In group 2

Less reactive than Alkali Metals

Effective Nuclear Charge

the effect of having more protons in the nucleus and will attract electrons more strongly

Electron Shielding

Protons pull in valence electrons and core electrons push away valence electrons

When does electron shielding increase?

When going down a group

When does ENC increase?

When going across a period

When does the atomic radius increase and decrease?

It increases when going down a group and decreases across a period

Atomic Radius

the distance between the nucleus and the valence electrons

Ionization energy

The amount of energy needed to remove an electron

When does ionization energy increase and decrease?

It increases when going across a period and decreases when going down a group

When does metallic character increase and decrease?

It increases down a group and decreases across a period

Electric affinity

The energy change that happens when an atom gains an electron

When does electric affinity increase and decrease?

It decreases down a group and increases across a period

Which groups form cations?

Groups 1 and 2

Which groups form anions

Groups 15, 16, and 17Cations in ionic bonds

Anions in ionic bonds

Non-metal, gains an electron, negatively charged

Properties of ionic compounds

Good conductors of electricity when dissolved in water, do not conduct electricity in the solid state, high melting point

Electrostatic interactions

Hold ionic compounds together

Monoatomic ion

an ion that consists of a single atom with a positive or negative charge

The stock system

used to name elements that can form more than one kind of cation. Uses roman numerals to indicate the charge

Names of main group metal ions

The name of the element + ion

Names of main group non-metal ions

The first part of the element + ide

Polyatomic ions

Ions that are made of a group of atoms that are covalently bonded together and have a charge

How do polyatomic ions behave

As a single unit, like a molecule

-ite

One less oxygen atom than the -ate ending

-ate

One more oxygen atom than the -ite ending

Chemical formula

shows the numbers of atoms of each element in the smallest representative unit of a substance

Binary compound

a compound composed of two elements

Octet rule

States that atoms tend to form bonds so that each atom has eight electrons in its valence electron shell. Cations lose electrons and anions gain electrons

ionic bond

An electrostatic attraction that holds oppositely charged ions together

Ionic compound

An electrically neutral compound made of cations and anions

Crystal lattice

An orderly, repeating three-dimensional pattern of many ions, atoms, or molecules

Lattice energy

A measure of the strength of bonds in an ionic compound and depends on the electrostatic force between the ions

If the distance between the ions is smaller, the bonds are…

stronger

Structure of the crystal lattice depends on…

the size and charge of the ions in the compound

Unit cell

A model that shows the smallest number of particles possible to represent the arrangement of ions

What dissolves many ionic compounds?

Water

When can ions conduct electricity?

When the compounds are dissolved in water and the ions are free to move

The melting point of an ionic compound is…

high