The Periodic Table and The Periodic Law

Development of the Modern Periodic Table

There were multiple people/scientist who contributed to the making of the periodic table as we know it…..

1. Antoine Lavoiser – compiled a list of the 23 elements known in the late 1790s.

2. John Newland – noticed that if the elements were arranged according to the atomic masses, the properties of the elements were repeated.

He called it the “Law of Octaves”.

Development of the Modern Periodic Table

3. Dimitri Mendeleev – is the person credited with making the 1st periodic table leaving spaces for the predicted elements in future. (It was based on the atomic masses)4. Henry Mosley – he then rearranged the periodic table based on atomic numbers and their characteristics, it is used till this date.

Modern Periodic Table (Recap)

Lavoiser – original 23 elements, 1790’sNewland – Arranged by atomic mass;

Law of Octaves – Properties repeatedMendeleev – Left spaces for future

elementsMoseley – Arranged by atomic numbers

and characteristics (current version)

Break-up of Periodic Table

How is table arranged?What are the rows called?What are the columns called?What are groups?What are families?

Break-up of the Periodic Table

Periods – Rows of the periodic table are called the periods. (7 periods at present)

Periodic Table

two rows below the periodic table are the lanthanide and actinide series

these rows fit after #57 and #89

they are only at the bottom to keep the width of the chart smaller

Break-up of Periodic Table

Period

Break-up of the Periodic Table

Groups/Family – Columns in the periodic table are called the groups. There a total of 18 but further classified:All “A” groups – representative elementsAll “B” groups – transition element

Groups have similar properties

Break-up of Periodic Table

Break-up of the Periodic Table

Within the groups and periods there is further classification:Metals

Non-metals

Metaloids

Break-up of the Periodic Table

Within the groups and periods there is further classification:Metals – located on the left, center and

bottom of the periodic table.

Break-up of Periodic Table

Break-up of the Periodic Table

Metals Usually, solids at room temperature. Solid at room temperature (all but Hg) malleable- can be rolled or hammered into sheets ductile- can be made into wire high tensile strength- can resist breakage when

pulled Lustrous – shiny most have silvery or grayish white

luster

Break-up of the Periodic Table

Within the groups and periods there is further classification:Metals – located on the left, center and

bottom of the periodic table. Non-metals – They are located on the right

side of the table.

Break-up of Periodic Table

Break-up of the Periodic Table

Non-metalsMany are gases If in solid form, they are brittle They are poor conductors of heat and electricity

Break-up of the Periodic Table

Within the groups and periods there is further classification:Metals – located on the left, center and

bottom of the periodic table. Non-metals – located on the right side of the

table.Metalloids – located on the “staircase” seen

in the periodic table.

Break-up of Periodic Table

Break-up of the Periodic Table

MetaloidsAlso, known as “semi-conductors” They exhibit properties of both metals and non-

metals.B, Si, Ge, As, Sb, Teall are solids at room temperature less malleable than metals but less brittle than

nonmetals

The s, p, d and f blocks

s-block elements – Groups 1 and 2 (1-A and 2-A)Group 1 (1-A) – are called Alkali metalsGroup 2 (2 – A) – are called Alkaline earth

metalsp-block elements – Groups 13 – 18 (3-A

=> 8-A)Group 17 (7-A) – are called HalogensGroup 18 (8-A) – are called Noble gases

The s, p, d and f blocks

d-block elements – are the B group elements (Groups 3 – 12 or 1B – 8B)They are called transition metals

f-block elements – are also within the B group placed at the bottom of the periodic table.They are known as the inner-transition

metalsThey are also classified as the Lanthanide

and Actinide series

Periodic Trends

What is an ion?An ion is a charged atom or molecule. It is charged because the number of

electrons do not equal the number of protons in the atom or molecule.

An atom can be positively charged or a negatively charged depending if the number of electrons in an atom is greater or less then the number of protons in the atom.

Ions

Periodic Trends

Periodic Trends

What is a trend?It is a characteristic that is repeated. (OR

the general course or prevailing tendency)

In the periodic table trends occur across a period and down the group. For example: The elements get less metallic across the period The elements become larger in size down a group.

Periodic Trends

Atomic Radius: It is the distance from the center of the nucleus to the outermost energy level where there are electrons.

It increases down the group. Why?The principal energy level increases.

It decreases across the period. Why?The energy level is the same but the

number of electrons increases and hence the electrostatic attraction increases.

Pg. 163

Periodic Trends

Ionic Radius: It is the distance from the center of the nucleus to the outermost energy level where there are electrons in an ion.

Positive ions are smallNegative ions are largePg. 166

Periodic Trends

Ionization Energy (I.E.): It is the amount of energy needed to remove an electron from an atom. (pg. 167 – 168)The amount of I.E. increases across a

period (that is left to right) WHY?The more electrons in the outermost orbital

hence more electrostatic attractionThe amount of I.E. decreases down a group

WHY?The electrons are further away form the nucleus

Periodic Trends

Electronegativity (E.N.): It is known as the ability of an atom to attract electrons. (pg. 169)E.N. increases across a periodE.N. decreases down a group

Noble gases are ignored.Fluorine has the largest E.N.Francium the smallest E.N.

Practice Problems

Which has a higher ionization energy?

1. Fe or Cu

2. Na or Rb

3. Ge or Ga

4. C or Si

Practice Problems

Which is bigger?

1. K or Li

2. B or Al

3. O or F

4. Fe2+ or Fe+

Practice Problems

Which has a greater electronegativity?

1. Ca or Sr

2. Cu or Ag

3. Al or Cl

4. F or N

Choose the element with the smaller radius

1. Chromium or tungsten

2. Cadmium or silver

3. Tin or antimony

Choose the element with the larger ionization energy

1. Magnesium or aluminum

2. Lithium or potassium

3. Yttrium or scandium

4. Carbon or germanium

Choose the element with the smaller electronegativity

1. Lead or Bismuth

2. Bromine or astatine

3. Gallium or phosphorus

4. Mercury or Gold