Chemistry Unit 1: Atomic Structure

Indirect

Direct relationship

Wavelike behaviour

Gamma rays: short wavelengths, high frequencies, high energy

Radio waves: long wavelengths, low frequencies, low energy

The waves created per second

The idea that light waves act as particles when they interact with matter.

In waves

No. Electrons do not orbit the nucleus like a solar system.

It moves to a higher energy level (excited state), emits the photon in a random direction, and returns to the original orbital (ground state) by releasing the same eV as it absorbed.

A particle representing a quantum of light or other electromagnetic radiation.

It emits the same energy of photon as it absorbed, but not necessarily in the same chunk.

As the electric current passes through the electron, it jumps between orbitals by emitting photons in random directions and gaining energy from the current. The colour it emits depends on the visible colour hydrogen absorbs in highest abundance.

An orbit is a path

An orbital is like a fence

The electron configuration shows how many electrons are in each orbital in any given element.

1. Write the energy level (there are 7)

2. Write the orbital (s, p, d, or f)

3. In superscript, write the number of electrons.

4. Do this in order by using the periodic table trick.

Example: Sodium: 1s22s22p63s1

*Bolded numbers represent superscript.

-A pattern in the periodic table that shows the order of orbitals and outermost orbital for each element.

Green: s

Blue: p

Pink: d

Purple: f

1. For the element you are trying to write, look at the period above it.

2. Select the noble gas of that period and put it in brackets.

3. Now add the rest of the electron configuration to get the desired element.

E.g. Lawrencium: [Rn] 7s26d105f5

*Bolded represents superscript

Electrons are added one at a time to the lowest energy orbitals available until all the electrons of the atom have been accounted for.

*Electrons are configured from lowest to highest energy level.

An orbital can hold a maximum of 2 electrons. To occupy the same orbital, 2 electrons must spin in opposite directions. When this occurs, electrons are said to be paired.

It is the only electron in an orbital.

Electrons occupy equal-energy orbitals so that a maximum number of unpaired electrons result.

*Bus analogy. You wouldn't sit by a stranger on a bus if there are pairs of seats still empty.

An ion has an electric charge due to the loss or gain of one or more electrons. Therefore, it will have more electrons in the electron configuration. Simply add or take away electrons from the normal configuration to match the ion's charge. E.g. Cl-, add an electron. K+ remove an electron.

Energy levels in an atom which are designated by quantum number n (the principle quantum number.

Each principle energy level is divided into one or more sublevels. These sublevels are labelled by the quantum number n (1-7) and a letter (s, p, d, or f) that corresponds to the type of sublevel.

Designated areas within a sublevel where electrons are statistically likely to be found. A sublevel may have 1 (s), 3 (p), 5(d), or 7(f) orbitals.

Alkali Metals

Alkaline Earth Metals

Transitional Metals

Chalcogens

Halogens

Noble Gases

Metals: Solids at room temp, shiny, malleable, ductile, good conductors, on the left side of the periodic table.

Semimetals/Metalloids: Have some properties of metals and some properties of nonmetals

Nonmetals: many gases at room temp, some solids, some liquid, not shiny, may be hard or soft, most are poor conducturs of heat/electricity

Valence electrons. Found in the outermost sublevels in an atom, farthest from the nucleus.

Because they have valence electrons in similar configurations. (same amount of electrons in the same orbital)

-Atomic Radius

-Ionic Size

-Ionization Energy

-Electronegativity and Chemical Bonds

The distance from the center of an atom's nucleus to its outermost electron.

Increases. Because as you move down a group, the principle quantum number of the outermost electrons increases. Electrons with a larger principle quantum number are found in orbitals that are farther away from the nucleus, which makes the atomic radius larger.

Decreases. Because as you move from left to right across a period the atoms' nuclei gain more protons. Atoms that have more protons in their nucleus exert a stronger pull on the electrons in a given principle quantum level. This stronger attractive force shrinks the electrons' orbitals and makes the atom smaller.

The size of an ion. Since an ion has an electric charge, the size differs from the atom.

Increase. Because as you move down a group the quantum number increases by 1. This means that another energy level has been added. Each subsequent energy level is larger than the one before.

Decreases. A positive ion has lost electrons. Electrons like to space themselves out equally around the nucleus. When an electron is lost, it reduces the repulsive forces between remaining electrons so they can pull closer together.

Second, the loss of its valence electrons results in the atom's outermost orbital becoming empty.

Decreases. A negative ion has gained electrons. This makes it larger than the atom form (for reasons similar to the previous question), but when you move from left to right the amount of electrons needed to stabilize the ion decreases, decreasing the size as well.

An atom's ionization energy is the energy needed to remove one of its electrons. Atoms with low ionization energies tend to form positive ions because it is easy for them to lose an electron. Atoms with high ionization energies tend to form negative ions because it is easier for them to gain an electron.

An element can have more than one ionization energy for each electron.

Decrease. As you move down a group, valence electrons get farther from the nucleus. Therefore, the protons in the nucleus hold onto these electrons more weakly. This is why the most reactive of elements are found at the bottom of the table.

Increase. Because as you move from left to right there is more force from the protons pulling on the electrons. This is called electrostatic attraction. It is harder to take an electron from an atom with a high number of protons.

A number which represents the affinity of an element to electrons in a chemical bond.

Decreases. Because the electron with which it is bonding to another element gets farther from its nucleus as you go down a group. The electrostatic attraction gets weaker.

Increases. Because there is a higher amount of protons as you move from left to right in the periodic table, increasing the electrostatic attraction of the proton to the electrons.

atoms with very similar electronegativities form a covalent bond. The electron pair is equally shared. This happens between atoms of the same element or atoms with an electronegativity difference equal or less than 0.4.

atoms with very different electronegativities form a covalent bond. The electron pairs is unequally shared. This happens between atoms with an electronegativity difference between 0.4 and 2. Because of a polar covalent bond, the atom with higher electronegativity will have a slightly negative charge while the atom with the lower electronegativity will have a slightly positive charge.

atoms have such a large difference between electronegativities that one atom with higher electronegativity "steals" the electron pair. The electronegativity of the two atoms must differ by 2.0 or more.

Because many compounds are ionic, and water is a polar molecule. Ionic dissolves in polar.

Oil is nonpolar. Water is polar. Polar and non polar do not mix.

1. The energy of electrons is quantized.

2. Electrons exhibit wavelike behaviour.

3. It is impossible to know the exact position and momentum of an electron at any moment.

In order for us to see something, we must see the light reflecting off of it. When an electron absorbs light, it moves, so we cannot see it.