Atomic Structure & Periodic Table Introduction

1. Atomic Structure & Periodic Table Introduction Physical Science JPHancock

2. The Atom • Basic building block of all matter • Elements on periodic table are represented as one neutral atom • Chemical symbols are abbreviated ways of representing elements • C, H, N, O • Na, Cl, Ne, Cu • NaCl, H2O, CO2

3. Parts of the Atom • Protons= (+) charge • Neutrons= (0) charge • Electrons= (-) charge • Quarks= smallest particles arranged in groups of threes to make p+, e-, or n0

4. History of the Atomic Model

6. Rutherford Experiment

7. Electron Cloud Model-1926 • “Probability Cloud” • Electrons orbit the nucleus in energy levels or orbits. • Why is it considered a “probability cloud”?

8. EVOLUTION OF ATOM

9. PERIODIC TABLE

10. The number of neutrons = mass number –atomic number • In a neutral atom the number of e- and number of p+ are equal • Every atom of the same element has the same number of protons • MASS NUMBER =ATOMIC MASS

11. ISOTOPES • Atoms of the same element with different numbers of neutrons

13. Atomic Mass Units • Do we now know how much atoms really weigh, in pounds or grams? • Yes, but we don't normally use those units for measuring the mass of an atom. It's much more convenient to use something called the atomic mass unit, or amu.

14. Using AMU is simplier! • One gram is about 600,000,000,000,000,000,000,000 amu (that's 600 sextillion, or a 6 followed by 23 zeros). A pound is just shy of 300 septillion amu--that is, 300,000,000,000,000,000,000,000,000. (26 zeros there.)

15. Periodic Table • 1869 Dmitri Mendeleev arranged the elements in order of their increasing atomicmasses • He discovered a pattern and was able to give rise to the modern periodic table

16. Mendeleev’s Periodic Table

17. PERIODIC LAW • The properties of elements are a periodic function of their atomic number • The properties change in a repeated pattern as we move across or down the periodic table • Elements are arranged by changes in physical and chemical properties

18. MODERN PERIODIC TABLE • 1913 Henry G.J. Moseley • Arranged the periodic table based on increasing atomic numbers • PERIODS or Series –horizontal rows 1-7 • GROUPS or Families-vertical columns 1-18 with similar properties

19. Properties of Groups • Elements of same group have same # valence electrons • Valence electrons- are the e- in the outermost energy level • Important role in chemical reactivity • Electrons closer to the nucleus have lower energy than those farther away

20. Properties of Series

21. Ionization Energy • Amount of energy needed to remove the outer electrons • As you move right to left the radius of the nucleus increases meaning the size(distance) between the nucleus and electrons is greater • As you move left to right the radius decreases meaning the electrons are valence electrons closer to the nucleus, held tighter and require more energy to remove

23. Atomic Radii

25. Electron Dot Diagrams • Used to represent valence electrons in bonding