# Periodic Table

## Periodic Trends:

Atoms have an electron cloud surrounding the nucleus

(the radius varies from element to element)

• As you move left to right across a period, the atomic radii generally DECREASES

• As you move down a group, the atomic radii generally INCREASES

Explanation:

when moving left to right, there is an increasing positive charge in the nucleus… pulling the electrons closer to the positive nucleus, therefore the reason why radii decreases

- basically saying, there’s more protons in the nucleus

when going down a group, the radii would increase due to the increase of energy levels. this means that there’s a greater distance between outer orbital and the nucleus… hence the increase in atomic radii

Ionization Energy in simple terms is basically how much an atom wants their electrons…

High ionization energy: Strong hold on to electrons

(unlikely to become positive ions)

Low ionization energy: Weak hold on to electrons

(likely to become positive ions)

• As you move across periods from left to right, ionization energy INCREASES

• As you move down groups, ionization energy DECREASES

Explanation:

when moving from left to right, the elements get closer to reaching their noble gas state, meaning they would want to hold on to their electrons more than giving it away

when moving down a group, there’s a bigger number of orbitals, and the valence electrons are further away from the nucleus, making it easier for the atom to let go of those electrons

Octet Rule: Atoms tend to gain, lose, or share electrons in order to acquire a full set of 8 valence electrons

Electronegativity is the ability of an element to attract electrons…or basically how bad does it want another electron

• As you move from left to right, the electronegativity INCREASES

• As you move down a group, the electronegativity DECREASES

Explanation:

electronegativity is how much an element wants electrons, so as you move right, the closer the element is to reaching 8 valence electrons, so they would want to attract another one

as you move down a group, the valence electrons are further away from the nucleus, so it would tend to lose more. Besides, the nucleus wouldn’t have enough power to attract more electrons

## Types of Elements:

Metals:

• mostly all to the left, and it’s 75% of all elements

• malleable, ductile, luster, and conducts electricity

• more metallic as you go down a group, towards the left

Nonmetals:

• mostly gases

• dull, poor electrical conductors

• mostly to the right of the table

• brittle and lack metallic luster in the solid phase

• doesn’t conduct heat/electricity in the solid phase

• NOBLE GASES ARE MONOATOMIC (don’t bond with other atoms)

Metalloids:

• some properties of metals, and others of nonmetals

• staircase that separates the metals/non-metals

• B, Si, Ge, As, Sb, Te

## Using the Period Table:

Elements in the same group have similar chemical and physical properties !

• Same number of valence electrons

• form the same kind of ions, meaning they’ll combine with other elements the same way

These groups are a family, and each has their own specific name to differentiate it

• Elements in each family react differently with other elements

Group 1: Alkali Metals

• Hydrogen doesn’t count, as it’s a non-metal ***

• 1 electron in the outer shell (valence electron)

• Soft and silvery metals

• VERY reactive, esp. with water

• Conducts electricity

Group 2: Alkaline Earth Metals

• 2 electrons in the outer shell

• White and malleable

• Reactive, but less than Alkali metals

• Conducts electricity

Groups in the middle: Transition Metals

• Groups in the middle

• Good conductors of heat/electricity

• Used for jewelry

• Bonds with many elements in varieties of shapes

Group 3: Boron Family

• 3 electrons in the outer shell

• most are metals, but boron is a METALLOID

Group 4: Carbon Family

• 4 electrons in the outer shell

• contains metals, metalloids, and a NON-METAL (carbon)

Group 5: Nitrogen Family

• 5 electrons in the outer shell

• could share electrons to form compounds

• contains metals, metalloids and non-metals

Group 6: Oxygen Family

• 6 electrons in the outer shell

• contains metals, metalloids, and non-metals

• reactive

Group 7: Halogens

• 7 electrons in the outer shell

• all are non-metals

• VERY reactive, and often bond with elements from group 1

• always found combined with another element in nature and stays DIATOMIC when by itself

Group 8: Noble Gases

• exist as gases

• non-metals

• 8 electrons in the outer shell

• helium, with 2 electrons in outer shell is an exception

• NOT REACTIVE with other elements, due to already full valence shell

## 3 types of Elements (characteristics)

### Metals:

Chemical properties:

• tend to lose electrons easily

• have low ionization energies

• form positive ions when combining with other atoms

Physical properties:

• good conductors of heat and electricity

• lustrous- reflect light, shine when they are polished

• flexible

• malleable

• ductile

• are solids at room temperature (except for mercury)

### Nonmetals:

chemical properties:

• tend to gain electrons

• produce covalent bonds by sharing electrons with other nonmetals

physical properties:

• exist as gases, molecular solids, or network solids at room temperature except BROMINE

• solids are brittle (not ductile or malleable)

• solids are dull

• poor conductors of heat and electricity

### Metalloids:

• elements at the border in between metals and nonmetals have some properties of both