the periodic table

The Periodic Table

late 1790’s Antoine Lavoisier made a list of known elements◦ contained 23 elements

1864 John Newlands looked further into organization◦ The Law of Octaves –

repeating trends every 8 elements

Organizing the Elements

Late 1800’s Russia Grouped elements with similar properties

into columns◦ 7 columns were formed

Noble Gases (8th Column) were later discovered Was able to predict properties of missing

elements When Germanium was discovered, it fit his

predictions

Dmitri Mendeleev

Does mass always increase throughout the periodic table?◦ NOPE

Tellurium (52) Iodine (53) Nickel (28) Argon (18) Potassium (19)

Question

The properties of the elements are a periodic function of their atomic masses◦ periodic means repeating, like the moon cycle,

every month it repeats

**atomic number was not known during Mendeleev’s time

Mendeleev’s Periodic Law

The properties of the elements are a periodic function of their atomic numbers

Using x-rays, Henry Moseley determined the number of protons per element◦ This is Atomic Number

Elements with similar e- configurations are in the same columns known as “groups” or “families”◦ Families familiar characteristics◦ Families have the same number of v.e.’s

Today’s Periodic Law

Rows are periods, each row designates a different nrg level

Columns are groups or families and contain elements with similar properties

Notable rows and columns◦ Rows:

4f – Lanthanides 5f - Actinides

◦ Columns: 1 or IA – Alkali Metals 2 or IIA – Alkaline Earth Metals 17 or VIIA – Halogens 18 or VIIIA – Noble gases

The Modern Periodic Table

“A” Groups

Filling the ‘s’ and ‘p’ sublevels

Contains both metals and non metals

Representative Elements

“B” Groups

Fills the ‘d’ sublevels

Made up of only metals

Transition Metals

Fill the ‘f’ sublevels

Lanthanides Actinides

Inner Transition Metals

Luster (shine) Ductile (pulled into wires) Malleable (hammerable and won’t shatter) Good conductors of heat and electricity

Have 3 or less v.e.’s so they tend to lose them◦ Usually no more than 3 v.e.’s

Includes transition metals, actinides and lanthanides

Metals

Brittle (most are gaseous) Good insulators, not typically good

conductors of heat or electricity

Have 5 or more v.e.’s, so they tend to gain (or share) e-’s

Nonmetals

Elements with properties of both metals and nonmetals

Located on the diagonal between metals and nonmetals

There are 8 metalloids Can lose or gain v.e.’s depending on their

placement on the periodic table

Metalloids

8 e- in the outer nrg level make an atom not reactive or stable◦ Metals lose their e-’s to achieve octet

They become positive ( + ) = cations◦ Families 15 (VA), 16 (VIA), 17 (VIIA) gain e- to

achieve octet They become negative ( - ) = anions

All elements WANT 8 e-’s to become stable

Octet Rule

The most active metals are in the lower left corner of the periodic table

The most active nonmetals are in the upper right corner of the periodic table

Reactivity

Fr

F

Most active metal

Most active nonmetal

ReactivityDecreases

ReactivityDecreases

The Periodic TablePeriodic Trends

Increases as you go down a group◦ More e- = bigger radius◦ Atoms are gaining nrg levels

Decreases as you go across a period◦ e- are being added to the same nrg level◦ Nuclear charge – force of attraction between e-

and nucleus◦ As you move across a period, more e- are being

attracted to the nucleus

Atomic Radii

INCREASES as you go DOWN a group because of nrg levels

DECREASES as you go ACROSS a group because of nuclear charge

Noble gases radii are found to be larger because they don’t interact with other atoms of the same element as most others do.

Atomic Radii

Atomic Radii

Atoms can lose or gain e- to complete or empty an outer nrg level◦ Every atom wants an octet

Ion – an atom that has a + or – charge Metals

◦ Lose e- giving them a + charge◦ Decreases their radius◦ These are cations

Nonmetals◦ Gain e- giving them a – charge◦ Increases their radius◦ These are anions

Ions

Cations◦ H+, Li+, Na+, Mg2+, Ca2+

Anions◦ F-, Cl-, O2-, S2-, N3-, P3-

**noble gases don’t have ions, they are stable and DO NOT IONIZE

*carbon doesn’t ionize a lot, it “shares”◦ When it does ionize, it gains 4 e-

Sizably increases its radius

Examples of Ions

Nrg needed to remove an e- from an atom◦ Unit = (kJ/mol)

ACROSS a period, it INCREASES◦ Due to increase in nuclear charge

DOWN a group, it DECREASES◦ Due to increased atomic radius and shielding effect

Metals = low I.E. Nonmetals = high I.E. (especially noble

gases)

Ionization Energy

Nrg needed to remove a second e- from an atom◦ Typically harder to remove a 2nd e-

**The higher the I.E., the more stable the atom.

2nd Ionization Energy

BeB

1s 2s 2p

1s 2s 2p

More stable, full/empty sublevels

Less stable, partial sublevels

The power of an atom in a molecule to ATTRACT e- to itself◦ Ability to “hold on to e- more”◦ DECREASES from top to bottom of group◦ INCREASES from left to right in periods◦ F has the highest E.N.

High E.N.’s gain e- and form (-) ions◦ The more stable an atom, the less likely it will

attract an e- Would result in (-)E.N.

High E.N. = High electron affinity

Electronegativity

Like tug-o-war◦ Big guy (high E.N.)◦ Little guy (low E.N.)

Electronegativity

FDecrease in E.N.

Decrease in E.N.

Most active metals (lower left) have the LOWEST E.N.

Fluorine has the highest E.N.

Noble Gases have NO E.N., because they don’t typically bond

No units for E.N. because it is a comparison

Deals with compounds and bonding

Facts