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Trends in the periodic table:

Trends in the periodic table:. Background. Electrons can jump between shells (Bohr’s model supported by line spectra) The electrons can be pushed so far that they escape the attraction of the nucleus Losing an electron is called ionization

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Trends in the periodic table:

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  1. Trends in the periodic table:

  2. Background • Electrons can jump between shells (Bohr’s model supported by line spectra) • The electrons can be pushed so far that they escape the attraction of the nucleus • Losing an electron is called ionization • An ion is an atom that has either a net positive or net negative charge • Q: what would the charge be on an atom that lost an electron? Gained two electrons? • A: +1 (because your losing a -ve electron) • A: -2 (because you gain 2 -ve electrons)

  3. Periodic trends in atomic size Atomic size generally increases down a group. Atomic size generally decreases from left to right across a period

  4. Periodic trends in ionisation energy When an atom gains or loses an electron it forms an ion. The energy required to remove an electron from a gaseous atom is known as the ionisation energy The first ionisation energy decreases moving down a group The first ionisation energy increases moving left to right across a period

  5. The atoms of metallic elements have low ionisation energies and form positive ions easily. • Cations (+ve ions) are always smaller than the neutral atoms from which they are formed due to increased attraction by nucleus for remaining electrons • The atoms of non-metallic elements readily form negative ions • Anions (-ve ions) are always larger than the neutral atom from which they are formed. Periodic trends in ionic size

  6. Electronegativity of an element is a measure of the degree too which an atom can attract an electron to itself. (Pauling’s scale). • Each atom, except the noble gases, is assigned an arbitrary number. F – 4.0, Cs & Fr 0.7 • Electronegativity; • increases across a period left to right • Decreases down a group Periodic trends in electronegativity

  7. Metallic character decreases across a period and increases down a group. Periodic trends in metallic characteristics

  8. An oxidant causes oxidation by gaining electrons but is itself reduced. An oxidant is also called an oxidising agent A reductantcauses reduction by losing electrons but is itself oxidised. A reductant is also called a reducing agent. Periodic trends in oxidising and reducing strength

  9. Alkali metals on line multiple choice Halogens on line multiple choice Transition metals, noble gases on line multiple choice Complete the revision questions page 167 (14 – 16) Complete the multiple choice questions pages 168, 169 (1 – 11) Complete the review questions 1, 6, 8, 9, 10, 13 Complete the exam practice questions 1, 3 Periodic Table on line questions REVIEW

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