Periodic Properties

When the atoms are arranged in terms of increasing atomic number certain basic chemical and physical properties will re-occur. These properties include:

Atomic radius, ionization energy, electron affinity, electronegativity.

Atomic Radius

decreases across the period (left to right) and increases down the group.

Zeff

As you go across the period there is a greater net force that penetrates to the valance electrons. This net force is called the effect nuclear charge.

As you go across the period the zeff

increases pulling the valence shell and it’s electrons closer in to the nucleus resulting in a decrease in radius.

(For Zeff)  As you go down the group the atomic number

Increases as well as the number of quantum levels.

The absorption of force by the electrons in the core is called the

shielding effect

Ionization Energy 1

The energy required to remove an electron or electrons from the valence shell of a gaseous atom.

For ionization energy, what is it’s trend?

it increases across the period and decreases down the group. 

what does it mean when “as you go across the period (left to right) the atomic radius is smaller”

The valence electrons are closer to the nucleus

An atom can have as many ionization energies as it has

valence electrons

Which element would require more energy to be ionized ? Helium or Cesium

Helium

Electron Affinity

The energy change that occurs when an electron or electrons are added to the valence shell of a gaseous atom.

For Electron Affinity, when it increases across the period it becomes more 

exothermic 

When does Electron Affinity become exothermic?

When the electron is added to some energy level.

Electron Affinity, when it decreases down the group it becomes more

endothermic 1

For electron Affinity, When the electron is added to a higher energy level it is

endothermic 2

Electron Negativity 

The ability of an atom to attract shared electrons to itself 

Chemical bonding

Any force that holds atoms together

There are several types of chemical bonds

Ionic bond, covalent bond, metallic bonding (bonding with metals), hydrogen bonding

Ionic Bonding

Involves the transfer of electrons and it occurs between n metal and non-metal

The Metal atom loses an electron(s) to form a positive ion called a 

cation

The non-metal atom gains the electron(s) to form a negative ion called an

anion

Ionic compounds in solution will conduct electricity. The reason is in

solution they break up into their corresponding ions. NaCl→Na + Cl

Sublimation (Ionic Bonding)

The amount of energy required to change one mole of a solid directly into a gas at constant pressure.

Ionization Energy

Is the minimal energy required to remove an electron from gaseous atom or ions

Bond Energy

The average energy required to break one mole of a specific type of chemical bond in the gaseous state

Affinity

The tendency or strength of attraction between 2 substances. Form chemical bonds

Lattice

The energy released when the constituent atoms are placed in their respective position on the crystal lattice.

Crystal Lattice

The symmetrical 3-Dimentional arrangementof atoms inside a crystal