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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
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