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Periodic table

Periodic table. Trends and patterns of properties in the periodic table. c. Organisation of the periodic table (notes). The vertical columns of the table are called groups or families. Element in the same group have similar but not identical characteristics Numbered from 1 to 18.

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Periodic table

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  1. Periodic table Trends and patterns of properties in the periodic table

  2. c

  3. Organisation of the periodic table(notes) • The vertical columns of the table are called groups or families. Element in the same group have similar but not identical characteristics • Numbered from 1 to 18. • Elements in the same group have the same number of outer shell electrons, and hence similar chemical properties.

  4. Organisation of the periodic table(notes) • The horizontal rows of the table are called periods. • Numbered from 1 to 7. • Each contains elements with electrons in the same outer shell.

  5. The trends of the periodic table • All elements in the same Group of the Periodic Table • have the same outer shell electron configuration. • All elements in the same Period of the Periodic Table have outer shell electrons • filling the same shell.

  6. Types of elements (notes) • There are three main types of elements: metals, non metals and metalloids • 1. Metals appear on the left hand side of the zig zag line that separates the periodic table • 2. Non metals appear on the right hand side of the zig zag line that separates the periodic table • 3. Elements on either side of the zigzag line have properties of both metals and non-metals. These elements are called metalloids.

  7. x

  8. Metals • Most elements are metals. 88 elements to the left of the stairstep line are metals or metal like elements. • Left side of the periodic table • Positive valencies Physical Properties of Metals: • Luster (shininess) • Good conductors of heat and electricity • High density (heavy for their size) • High melting point • Ductile (most metals can be drawn out into thin wires) • Malleable (most metals can be hammered into thin sheets) Chemical Properties of Metals: • Easily lose electrons • Corrode easily. Corrosion is a gradual wearing away. (Example: silver tarnishing and iron rusting)

  9. Non-metals • Nonmetals are found to the right of the stairstep line. Their characteristics are opposite those of metals. Physical Properties of Nonmetals: • No luster (dull appearance) • Poor conductor of heat and electricity • Brittle (breaks easily) • Not ductile • Not malleable • Low density • Low melting point Chemical Properties of Nonmetals: • Tend to gain electrons • Since metals tend to lose electrons and nonmetals tend to gain electrons, metals and nonmetals like to form compounds with each other. These compounds are called ionic compounds. When two or more nonmetals bond with each other, they form a covalent compound.

  10. Atomic properties • Many properties of atoms depend on the strength of attraction between the outer shell electrons and the nucleus • This attraction will depend on • The positive charge that attracts the other shell electrons • The distance of electrons from the nucleus

  11. In groups determine what will happen to each of these properties across a period and down a group • Core Charge: The attraction that an outer shell electron feels towards the nucleus • Atomic Size: Diameter of an atom • Ionisation Energy: Minimum amount of energy required to remove the highest energy electron from an atom (energy to steal an electron). • Electronegativity: Measure of the ability of an atom to attract an electron towards itself. (love of electrons)

  12. Core Charge What is it? • The attraction that an outer shell electron feels towards the nucleus. What happens down a group? • Constant • In the Alkaline metals there is always one electron in the outer shell. What happens across a period? • Increases; there are more electrons in the outer shell which are greatly attracted to the nucleus.

  13. Lithium has one electron in its outer shell and this is attracted to the protons in the nucleus. The outer shell electron does not feel the full attraction of the nucleus and therefore has a core charge of +1 • Chlorine has 7 electrons in its outer shell • What would its core charge be? • Across a period the core charge changes from +1 ,+ 2, +3, +4 etc.

  14. Atomic Size or Radius What is it? • Diameter of atom What happens down a group? • Increases • since there is an increase in the number of shells. What happens across a period? • Decreases • since there is an increase in core charge, the outer shell electrons are attracted closer to the nucleus (it’s the same shell but there are more electrons in the shell as you move across the period)

  15. Atomic radius decreases across a period • x

  16. Atomic radius increases down a group

  17. Trends in Ionisation energy • The ionization energy is the amount of energy it takes to detach one electron from a neutral atom • Or How much energy it takes to steal an electron!! • If its easy to steal a electron it has low ionisation energy • If its hard to steal an electron it has a high ionisation energy • The smaller the atom the harder to steal an electron • The larger the atom the easier it is to steal an electron e

  18. e e e e e e e Ionisation Energy e • What is it? • Amount of energy required to remove the highest energy electron from an atom. (or steal one electron) • What happens down a group? • Decreases; since the size of the atom is increasing, the attraction is weaker between the outer shell electrons and the nucleus. Therefore electrons are easier to remove. • What happens across a period? • Increases; since there is an increase in core charge, the attraction is greater between the outer shell electrons and the nucleus. Therefore electrons are harder to remove.

  19. As the period begins it does not take a lot of energy to remove an electron from Li but as you go across the period it takes more and more energy to take an electron away

  20. b

  21. Electronegativity • http://www.youtube.com/watch?v=93G_FqpGFGY • http://www.youtube.com/watch?v=d-hEkyYUXSo • http://www.youtube.com/watch?v=x4WEqWlp29U

  22. Electronegativity • What is it? • Measure of the ability of an atom to attract an electron towards itself or love of electrons! • What happens down a group? • Decreases; since the electrons are further from the nucleus, there is a weaker attraction • What happens across a period? • Increases; since there is an increase in core charge, there is a greater attraction of the outer shell electrons to the nucleus. e

  23. c

  24. Reactivity of Metals • http://www.youtube.com/watch?v=GVoJZkmAAfA(Group 1 in water) • http://www.youtube.com/watch?v=V2TimLxskZw (Magnesium in water) • http://www.youtube.com/watch?v=nSgIr1Wba_g&feature=related(Calcium in water) • Group One (Alkaline Metals) are more reactive than Group 2 (Alkaline Earths) • As you go down a group metals become more reactive • This happens because as you go down a group atoms get larger and metals tend to donate electrons in reactions.

  25. Reactivity of Non metals • Look at table 3.3 to see which Halogen is most reactive • Reactivity decreases down the group • Why? Think about atomic properties • Non metals tend to form negative ions (they gain electrons from other atoms) • Electronegativity or love of electrons is strongest with Fluorine and decreases down the group.

  26. Noble Gases • Found in group 18 (the last column of the periodic table.) • Do not react easily with other elements, as they have a full outer shell.

  27. Homework • Pg 51 Q 16 a and b, 18, 21, 22, 27

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