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The Periodic Table

The Periodic Table. Periodic Table Groups to Know…. The Periodic Table. The elements are arranged in rows and columns on the Periodic Table according to the similarities in their properties Metals are found on the left side and bottom of the Periodic Table

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The Periodic Table

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  1. The Periodic Table

  2. Periodic Table Groups to Know…

  3. The Periodic Table • The elements are arranged in rows and columns on the Periodic Table according to the similarities in their properties • Metals are found on the left side and bottom of the Periodic Table • Non-metals are found on the right side of the Periodic Table

  4. The Periodic Table • Metalloids are arranged in a diagonal pattern between the metals and non-metals

  5. The Periodic Table • A column of elements is known as a GROUP • The group number corresponds to the number of valence electrons • A horizontal row of elements is known as a PERIOD • The period number corresponds to the number of shells containing electrons

  6. The Periodic Table • Four groups have characteristic family names : • Group I Alkali metals • Group II Alkaline earth metals • Group VII Halogens • Group VIII Noble (inert) gases

  7. The Periodic Table • The large block of elements between groups 2 and 3 forms a transition between the metals on the left and non-metals on the right and are called the Transition metals • Elements 58-71 are called Lanthanides (or rare earth elements) because of their rare occurrence in nature

  8. The Periodic Table • Elements 90-103 are called Actinides and these are all radioactive elements • Elements with atomic numbers more than 92 are called transuranium elements. They are not found in nature and are synthesised in the laboratory

  9. Group I: Alkali metals • Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Caesium (Cs) and Francium (Fr) • Each has one electron in the valence shell • Lose the one electron in chemical reactions to form the M+ ion

  10. Group I: Alkali metals • Very reactive with water (stored under paraffin oil to exclude moisture) • Form white crystalline solids which are soluble in water

  11. Group II: Alkaline Earth metals • Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), Radium (Ra) • Each has two electrons in its valence shell • Lose 2 electrons to form M2+ ions in chemical reactions

  12. Group II: Alkaline Earth metals • Less reactive with water than group I metals • From white crystalline solids, some of which are soluble in water

  13. Group IV • Carbon is a non metal, Silicon and Germanium are metalloids and Tin and Lead are metals • 4 valence electrons • Carbon, silicon and germanium react to form compounds of general formula XY4 where X is the group IV element • Tin and lead form +2 and +4 ions

  14. Group VII: Halogens • Exist as diatomic molecules: Fluorine F2 Chlorine Cl2 Bromine Br2 Iodine I2 Astatine At2 • Are very reactive non metals • Occur in nature as the halide ions X- in salts when reacted with metals (i.e. they have gained one electron)

  15. Group VIII: The Noble Gases • Helium He Argon Ar Neon Ne Krypton Kr Xenon Xe Radon Rn • Are unreactive non metals due to their stable electronic configuration • Do not usually form compounds (He and Ne do not form compounds)

  16. The Transition Elements • Located between Group II and III • Have relatively high melting points and densities • Usually form coloured ions in solutions Copper: blue Iron(II): green Iron(III): brown Chromium: orange Nickel: green

  17. Trends in the Periodic Table • Elements within a group have the same number and distribution of valence electrons • = some patterns/trends in behaviour • Reactivity • Atomic Radius • Electronegativity

  18. Trend: Reactivity • Most reactive: • Alkali Metals  lose one electron to from an octet • Halogens  gain one electron to from an octet

  19. Trend: Reactivity Increasing Increasing Increasing Increasing

  20. Trend: Atomic Radius • Atomic Radius = a measurement of the size of an atom (radii = plural) • Atomic radii increases as we move down a group • More electron shells = bigger • With each additional energy level the attractive forces of the nucleus (protons, +) is reduced = shielding effect • Valence electrons (outer shell) are not as strongly attracted = bigger radius

  21. Trend: Atomic Radius • Atomic radii decreases from left to right across a period • Moving from left to right atoms have more protons • Attractive forces of the nucleus (+) for valence electrons (-) increase • Electrons pulled closer to the nucleus = smaller radius

  22. Increasing Increasing

  23. Trend: Electronegativity • Electronegativity= a number that describes the ability of an atom to attract electrons • Provides a means of prediction the nature of the forces that hold a pair of atoms together in a bond • More electronegative = stronger pull on electrons being shared • Less electronegative = weaker pull on electrons being shared

  24. Trend: Electronegativity Increasing Increasing

  25. Atomic Radius & Electronegativity • Electronegativityincreases when the atomic radius is small • Electronegativitydecreases when the atomic radius is large • Large atomic radius = valence electrons are further from the nucleus • Less attractive forces holding the valence electrons • Less attractive forces to pull electrons to t he atom

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