UPCAT SCI - CHEM PERIODIC TABLE

Atomic Radius Trend

Increases DOWN and LEFT. (Largest neutral element: Francium / Fr)

Why does Atomic Radius increase DOWN a group?

New principal energy levels (electron shells) are added, making the atom physically larger.

Why does Atomic Radius decrease LEFT to RIGHT?

More protons are added to the nucleus, creating a stronger positive pull that reels the electron shells in tighter.

Ionization Energy

The energy required to remove a valence electron from an isolated gaseous atom. Increases UP and RIGHT.

Ionization Energy Champion

Helium (He). It is tiny, close to the nucleus, has zero inner core shielding, and has a perfectly full 1s² subshell.

Electronegativity

An atom's offensive ability to pull shared electrons toward itself inside a chemical bond. Increases UP and RIGHT.

Electronegativity Champion

Fluorine (F). It is the smallest bonding atom with a massive net positive pull (+7 effective nuclear charge).

Why do Noble Gases have 0 Electronegativity?

Their valence shells (s² p⁶) are already perfectly full and stable, meaning they do not form chemical bonds or attract outside electrons.

Electron Affinity

The actual energy released when an isolated gaseous atom takes in a free electron or how accepting for an electron an atom is. Increases UP and RIGHT.

Electron Affinity Champion (The Trap Question)

Chlorine (Cl). Its larger n=3 shell accommodates an extra electron comfortably without crowded repulsion.

Why does Chlorine beat Fluorine in Electron Affinity?

Fluorine is too tiny (n=2). Its 7 valence electrons are packed so tightly that they cause intense electron-electron repulsion, resisting a new electron.

Metallic Character

An atom's willingness to lose electrons and behave like a metal. Increases DOWN and LEFT (Winner: Francium / Fr).

Ionic Radius Rule for Cations (+)

Cations always SHRINK. Losing an electron often removes an outer shell layer and increases the remaining protons' proportional grip.

Ionic Radius Rule for Anions (-)

Anions always EXPAND. Adding an extra negative electron into the same shell causes massive electron-electron repulsion, puffing the cloud outward.

• Malleable, usually solid and can be plastically deformed

• Can conduct electricity and heat well.

• High Melting Point and densities

• Low electronegavitiy and ionization energy

Metal

• High Ionization energy and electronegativity

• Poor conductor of electricity

• Brittle solids

Nonmetals

Horizontal Rows in the PEriodic table

Period

COlumns in the periodic table

Groups

What group reacts violently with water and can have a +1 charge

G1 Alkali Metals

What group can have a +2 charge and is somewhat reactive in standard temperature and pressure

G2 Alkaline Earth Metals

What group has extremely high electronegativity and is very reactive

Group 17 or 7A Halogens

What group is stable due to complete valence shells, making them usually unreactive

Group 8A or 18 Noble Gases

Group that usually has high oxidation states

Transition Metals