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Chapter 4

Periodic Table. Chapter 4. History of the Periodic Table. Dmitri Mendeleev wrote the first periodic table. He arranged elements in order of atomic mass. He noticed repeating properties . Mendeleev’s periodic table. Moseley’s periodic table.

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Chapter 4

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  1. Periodic Table Chapter 4

  2. History of the Periodic Table • Dmitri Mendeleev wrote the first periodic table. • He arranged elements in order of atomic mass. • He noticed repeating properties.

  3. Mendeleev’s periodic table

  4. Moseley’s periodic table • Moseley rearranged the elements by atomic number.

  5. Organization of the p.t. • There are 18 groups or families (columns). • All elements in a group have the same number of outer level (valence) electrons. • There are 7 periods (rows). • All elements in a period have electrons on the same energy level.

  6. Group 1 metals • Called alkali metals. • They all react violently with nonmetals. • They have 1 valence electron which they lose very easily. • Li is the least reactive, Fr is the most reactive • They are all soft • They are not found in nature because they are so reactive. Why?

  7. Group 2 metals • Called Alkaline Earth Metals • They have 2 valence electrons. • They are harder and less reactive than group 1 metals.

  8. Group 17 • Called halogens • Most reactive nonmetals • They all have 7 valence electrons • They react with metals to form “salts” Why?

  9. Group 18 • Noble gases • They don’t react • They have 8 valence electrons (except Helium) • This is a full outer level Why?

  10. Metals • Most elements are metals • Metals are good conductors of heat and electricity • Metals are ductile (can be squeezed into a wire) • Metals are malleable (can be hammered or bent)

  11. Transition Metals • Groups 3 – 12 • They have many different properties • Less reactive than alkaline earth metals • Some are fairly non-reactive (Cu, Ag, Au) • Tungsten has the highest melting point • Mercury is a liquid with high density • Metals can be mixed together (alloy) to produce desirable properties.

  12. F - Block • Lanthanides (group 4f) • #58 – 71 • Actinides (group 5f) • #90 - 103

  13. Ionization Energy • The energy required to remove an electron. • If an electron is easy to remove, it takes little energy. • Period Trend • As you go from left to right across the period, it is harder to remove an electron – I.E. increases • Group Trend • As you go down a group, it is easier to remove an electron – I.E. decreases

  14. Atomic Radius radius • Size of an atom Half the distance between 2 adjacent nuclei

  15. Atomic Radius • Period Trend • As you go from left to right across a period, atomic radius decreases • Group Trend • As you go down a period, atomic radius increases.

  16. Electron Affinity • Energy change when an atom gains an electron. • Period Trend • As you go from left to right across a period, electron affinity increases. • Group Trend • As you go down a group, electron affinity decreases.

  17. Electronegativity • Ability to attract electrons • 0 – 4 • Period Trend • As you go from left to right across a period, electronegativity increases. • Group Trend • As you go down a group, electronegativity decreases.

  18. Ions • An ion is an atom that has lost or gained electrons. • Lose electrons – (+ ion) • Called cation • Gain electrons – (- ion) • Called anion

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