Periodic Trends : Chemistry

Ionization Energy Trend: Group

The ionization energy of the elements decreases as one moves down a given group because the electrons are held in higher-energy orbitals, further from the nucleus and therefore are not as tightly bound (easier to remove).

Nuclear charge

The nuclear charge is the total charge of all the protons in the nucleus. It has the same value as the atomic number. The nuclear charge increases you go across the periodic table.

Nuclear charge Trends: Periodic

The periodic table tendency for effective nuclear charge: Increase across a period (due to increasing nuclear charge with no accompanying increase in shielding effect).

Ionization Energy Trend: Periodic

The ionization energy of an element increases as one moves across a period in the periodic table because the electrons are held tighter by the higher effective nuclear charge.

Special aspects of Boiling/ Melting Points

-Gasses need to be taken into consideration as they will need to be much lower temperatures for boiling. -As a result of their strong bonds, metals are much harder to melt. This is seen in the transition elements like Tungsten with a +6 ionic charge. -Metalloids near the stair step line have varying melting points as the bonds range from semi strong to weak.

Electronegativity special aspects & exceptions

-Noble gases & inner transition metals (lanthanides & actinides) & transition metals -Noble gases have complete outer shell and don't (usually) attract electrons -Lanthanides & actinides outer shell is empty so they also don't attract electrons -Therefore, these groups don't have electronegativity values -Fluorine is the most electronegative element and francium is the least -Transition metals have electronegativity values, but their metallic properties hinder their ability to attract electrons (as compared to other elements)

Atomic Size special aspect

-Shield Effect: describes the attraction between an electron and the nucleus in any atom with more than one electron shell. Shielding effect can be defined as a reduction in the nuclear charge on the electron cloud, due to a difference in the attraction forces of the electrons on the nucleus.

Electronegativity

A measure of the ability of an atom to pull off or attract electrons.

Electronegativity trends : group

As you move down a group (column), electronegativity decreases (as you move up, it increases) due to the distance between the nucleus and the valence electron shell. This decreases the attraction.

Shielding Trends: Periodic

Constant across a given period because inner electrons are constant

Nuclear charge Trends: Group

Decrease down a group (although nuclear charge increases down a group, shielding effect more than counters its effect).

Nuclear charge special aspects

Effective nuclear charge - the attractive positive charge of nuclear protons acting on valence electrons. 1. The effective nuclear charge is always less than the total number of protons present in a nucleus due to shielding effect. 2. Effective nuclear charge is behind all other periodic table tendencies. Equation: An estimate of effective nuclear charge can be obtained from Zeff = Z - S, where Zeff = effective nuclear charge, Z = atomic number, and, S = the screening constant.

Electronegativity trends: periodic

Electronegativity increases as you move from left to right across a period because the number of charges on the nucleus increases.

Atomic Size: Trends- group

Group: The size generally increases down each group (column). With the presence of additional energy levels, the atomic radius then increases and the valence electrons occupy higher levels because , and the elections go further and further away from the nucleus.

Boiling/ Melting Points

Melting point and boiling point both describe temperature and at which phase changes occur. The main difference between melting point and boiling point is, melting point describes the temperature at which solids and liquid phases are in a state of balance known as equilibrium. Boiling point is the temperature at which the vapor pressure is equal to the pressure outside of the liquid.

Boiling/ Melting Points Trends

Melting points are varied and do not generally form a distinguishable trend across the periodic table. However, certain conclusions can be drawn from the graph below. The non-metal carbon possesses the highest boiling point of all the elements. The semi-metal boron also possesses a high melting point.

Shielding special aspects

Not really any special aspects because it's a pretty straightforward pattern.

Atomic Size: Trends- periodic

Periodic: The size generally decreases along each period (row) of the table from left to right. As the atomic number increases along each period of the periodic table, the newly added electrons go into the same outer shell and cause the atomic radius to decrease (this is because there's an increase in nuclear charge).

Shielding

Shielding electrons are the electrons that are in between the nucleus and the valence electrons; They are the inner electrons that shield the outer electrons from the attractive force of the positive charge in the nucleus. The more energy levels between the valence electrons and the nucleus, the more shielding.

Shielding Trends: Group

Shielding increases as you move down a column in the periodic table because there are more electrons and therefore more energy levels, because Increases going down a group because of increasing inner elecrtons

Atomic Size

Size of atom depending on how far away the outermost electrons are from the nucleus.

Ionization Energy special aspects

Some elements have several ionization energy, in this case it is referred as "first ionization energy," or T, "second ionization energy," or 'I2'; where i is the electron lost. Also, Ionization is endothermic, meaning that the atom or molecule increases its internal energy, or takes energy from an outside source. Equation: 1st: Na --> Na+ + e- 2nd: Na+ --> Na2+ + e- 

Ionization Energy

is qualitatively defined as the amount of energy required to remove the most loosely bound electron, the valence electron, of an isolated gaseous atom to form a cation. The first or initial ionization energy or Ei of an atom or molecule is the energy required to remove one mole of electrons from one mole of isolated gaseous atoms or ions. Also Known As: ionization potential, IE, IP, ΔH°