Lesson 1

MENDELEEV’S PERIODIC TABLE

Mendeleev proposed his periodic law: The properties of elements vary periodically with

their atomic weights.

Mendeleev’s periodic table: Arranged the elements according to similar properties

and relative atomic mass. Allowed the prediction of undiscovered elements.

GROUP 1 (ALKALI METALS)

Metals Shiny and Soft Highly reactive with water and oxygen

Sodium and Potassium Demonstration

https://www.youtube.com/watch?v=sNdijknRxfU

GROUP 2 (ALKALINE EARTH METALS)

Metals Reactive but less so than group 1

Magnesium Demonstration https://www.youtube.com/watch?v=B2ZPrg9IVEo

GROUPS 3-12 (TRANSITION METALS)

Metals Range of properties Varying oxidation states

Vanadium

GROUP 17 (HALOGENS)

Highly reactive (as you move up more reactive)

Non-metals

https://www.youtube.com/watch?v=yP0U5rGWqdg

GROUP 18 (INERT GASES)

Basically non-reactive Low boiling points and all gases at room

temperature.

WHY DOES BREATHING IN HELIUM CHANGE OUR VOICE?WHY DO HELIUM BALLOONS FLOAT?

https://www.youtube.com/watch?v=JjJOS0BpgnM

REVIEW Determine the element and whether it is in the ground or excited state. a) 1s22s22p63s1

b) 1s22s22p53s2

c) 1s22s22p63s23p63d2

Name an element with similar properties to:d) Berylliume) Calciumf) Magnesium

WHAT DO YOU NOTICE ABOUT ELEMENT PROPERTIES?

Variations of the chemical properties of elements across a period and similarities down a group are all associated with the electronic

configurations of their atoms. In particular, the outershell electron

configuration.

In general, elements with the same number of electrons in their

outershell will react in a similar way!

BLOCKS OF ELEMENTS

QUESTIONS 1c, 2, 4cd, 5, 6c (pg. 42) and worksheet 5

ATOMIC PROPERTIES Include: Atomic radius/size Electronegativity Ionisation energy

THERE ARE TWO MAIN FACTORS WHICH INFLUENCE

ATOMIC PROPERTIES!

1. CORE CHARGEThe sum positive charge of the nucleus acting on

the valence (outer shell) electrons.This takes into account the effect of shielding from

the inner shell electrons.Core charge= No. Protons - No. inner shell electrons

E.g. Lithium. 3 protons, 2 inner electrons.Core charge, 3-2 = 11. What is the core charge on the valence electrons

of Period 2: Lithium, Boron, Nitrogen, Neon? Period 3: Sodium, Aluminum, Phosphorus, Argon?

2. Core charge increases across a period and remains the same down a group.

2. DISTANCE FROM THE NUCLEUS The distance

between the outer shell electrons and nucleus.

Distance increases as the number of shells increases.

As the distance increases, the attraction between the nucleus and outer shell electrons decreases.

Distance increases down a group and remains the same across a period.

Period 1

2

3

4

1

1

1

1

ATOMIC PROPERTIES Include: Atomic radius/ size Electronegativity Ionisation energy

ATOMIC RADIUS/SIZE This is how we measure the size of an atom.Atomic radius- one half of the distance

between the nuclei of two atoms of the same element.

It is usually expressed in picometres (1trillion pm is 1 m)

ATOMIC RADIUS/ SIZE As core charge

increases the outer electrons are more tightly held and therefore the atomic size decreases.

Atomic size decreases across a period

As distance from the nucleus increases atomic size increases.

Atomic size increases down a group

Internet explorer

ELECTRONEGATIVITY

Oxygen Hydrogene-

e-

• The ability of an atom that is bonded to another atom to attract the bonding electrons towards itself.

• Can think of it as how much an atom wants electrons.

ELECTRONEGATIVITY The electron attracting power of particular

element. As the core charge increases the

Electronegativity increases ad electrons are pulled towards the nucleus.

Across a period Electronegativity increases As the electrons get further from the nucleus, the

nucleus can’t pull electrons towards them as strongly.

Down a group Electronegativity decreases1. Where are the most electronegative

elements found? In the top right of the periodic table (N, O, F)

IONISATION ENERGIES

Ionisation energy- The amount of energy required to remove an electron from an atom. The 1st ionisation energy is the energy needed to

remove one outer shell electron from an atom.The 2nd ionisation energy is the energy needed

to remove the 2nd electron from an atom.

Na

http://www.youtube.com/watch?v=ZWLftJBoNc8

IONISATION ENERGIES The 1st ionisation

energy is the energy needed to remove one outer shell electron.

As the core charge increases the hold on the electrons increases and ionisation energy increases.

As distance increases, ionisation energy decreases.

1. Across a period ionisation energies increase

2. Down a group ionisation energies decrease

SUCCESSIVE IONIZATION ENERGIES

As you progress through the electrons they become successively harder to ionize.As you move to the next shell there is a big jump in the energy required to ionize the electron.We can use this to identify the element.

Which element in the periodic table would you expect to have the

- BIGGEST ionisation energy- SMALLEST ionisation energy

Why?

Draw a Sodium atom and a Sodium ion.

Which is going to be smaller and WHY?

COMPOUND These, like elements are

pure substances. Elements: pure

substance made of one type of atom.

Compound: Substance made of two or more types of atoms. (atoms bonded together)

One type of compound will always have the same ratio of different types of atoms.

HEINEMANNChapter 3 Pg 48: 9bc Pg 51: Chapter review: 16, 18, 19, 20, 21, 22, 25, 29. Workbook: Worksheet 6Read page 50-51 of worksheet textbook.

11F Atomic theory, periodic table and trends test next Tuesday 12/2/13