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Exploring the Periodic Table: Patterns, Elements, and Valence Electrons

Discover the Periodic Table's organization, from Mendeleev's initial design to Moseley's modern arrangement by atomic number. Learn about energy levels, electron configurations, valence electrons, and the properties of different groups of elements. Explore how elements are grouped into families and periods based on their atomic properties. Dive into the significance of valence electrons and their role in determining chemical properties. Uncover the unique characteristics of alkali metals, alkaline metals, halogens, and noble gases. This comprehensive guide provides insights into the structure and composition of the Periodic Table.

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Exploring the Periodic Table: Patterns, Elements, and Valence Electrons

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  1. Periodic Table Section 18.3

  2. Periodic Table • Periodic- Repeated in a pattern • Elements are ordered by: • increasing atomic number • changes in physical & chemical properties • Mendeleev- Ordered elements by atomic mass • Left blank places in his table to line up elements according to their properties • Elements were later discovered and fit into the places he left blank

  3. Mendeleev

  4. Periodic Table • Moseley- organized elements by atomic number rather than atomic mass • Same arrangement as today • Groups/Families- vertical columns of the periodic table • Rows of Periodic Table- periods • Electrons • Around the nucleus in an electron cloud • Energy levels dictate location of electrons • Closer to nucleus = less energy • Fill energy levels from inner to outer levels

  5. Electrons • Electrons in outer shell – determine chemical properties of elements • Complete outer shell- needs 8 electrons to be stable • Energy levels and # of electrons in each: • Level 1 Holds 2 • Level 2 Holds 8 • Level 3 Holds 18 • Level 4 Holds 32

  6. Energy levels of electrons • Sublevel # e in sublevel Shape • s 2 sphere • p 6 dumbbell • d 10 double dumbbell • f 14 complex • http://library.thinkquest.org/3659/structures/shapes.html

  7. Energy levels of electrons • Level 1 s 2 electrons • Level 2 s & p 2 + 6 = 8 electrons • Level 3 s, p, d 2 + 6 + 10 = 18 e- • Level 4 s,p,d,f 2 + 6 + 10 + 14 = 32 e- • Valence Electrons • Group 1A – 8A have 1-8 valence electrons

  8. Periodic Table, Valence electrons, and Diatomics

  9. Dot Diagrams • Electron dot diagram (or Lewis dot diagram) - A symbol of an element surrounded by dots to represent electrons in the outer energy level • First 2 electrons go together • Next electrons go one on each side, then start to double up

  10. Valence electrons • http://www.ausetute.com.au/lewisstr.html • Properties of elements in the same group- similar due to same # of valence electrons • Alkali metals- group 1A- very reactive metals • Alkaline metals- group 2 A- less reactive than alkali • Halogens- group 7A • Likely to react with Alkali metals- group 1A

  11. Arrangement of Periodic Table • Noble Gases- group 8A- not reactive- don’t form compounds

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