Day 1 atomic structure

1. Day 1 atomic structure Objective: SWBAT manipulate a virtual model of an atom in order to • describe subatomic structure, net charge, atomic number and mass number • distinguish between neutral, stable atoms, ions and isotopes • construct 2D atomic models & nuclear symbols Warm-up: • Review: what are the defining features of an element? • Discuss at your table: How would you define an “atom”?

2. Element Atom

3. Evolution of the Atomic Model • Most recently…

4. Building An Atom http://phet.colorado.edu/en/simulation/build-an-atom

5. Drawing Atoms:OR + 0

6. Day 2 Objective: SWBAT manipulate a virtual model of an atom in order to • describe subatomic structure, net charge, atomic number and mass number • distinguish between neutral, stable atoms, ions and isotopes • construct 2D atomic models & nuclear symbols

7. Three Particles, Two Charges

8. Structure of an atom

9. Number of protons contained in an atom Determines the element Every element of that kind has the same number of protons Atomic Number Mass Number • Number of protons and neutrons in an atom (p+ + n0) • Can change for various isotopes

10. Mass Number Protons have a mass Neutrons (although neutral) have a mass similar to protons Electrons have a mass so small we don’t account for it in calculating the mass Therefore the mass number is the sum of all protons and neutrons within the atom Mass Number = P + N When to use: When determining composition of a single atom! (this is not what’s on the PT)

11. Atomic Mass / Molar Mass The atomic mass is a “weighted” average mass of all the stable isotopes of the element. Finding Atomic Mass For every stable isotope: Multiply the isotope’s mass number x % abundance (how often the element is found in that form) written as a decimal After you do this for each stable isotope, add them all up Av. Atomic Mass = Σ(Mass # x Abundance) Not the Mass Number!!! – Atomic Mass is on the PT This symbol means sum (add up all of these after you multiply)

12. Example: Carbon • Carbon – 12 (98.9% written as a decimal = .989) • Carbon – 13 (1.1% = .011) • Carbon – 14 (Not a stable isotope so not counted) • Av. Atomic Mass = (12 x .989) + (13 x .011) = 12.011

13. Differing number electrons (e-) changes overall charge of the atom Cations (positive) Anions (negative) Ions Isotopes • Differing number of neutrons (n0) • Changes Mass Number

14. Ions – Anions/Cations Anions (non-metals) An atom with a net negative charge More electrons than protons Br- contains 35 protons, 36 electrons (-1) Ca+ions (metals) An atom with a net positive charge More protons than electrons Mg2+ contains 12 protons, 10 electrons (+2) Remember: You NEVER change the number of protons, just electrons

15. Isotopes An isotope is an element that contains a different number of neutrons. Affects the molar mass of the element Longhand notation Element – Mass Number Carbon – 12 Carbon – 14 Shorthand notation Charge Mass# X Atomic #

16. All elements want to become like the noble gases! Alkali Metals – lose 1 e Alkaline Earths – Lose 2 e IIIA – Lose 3 e IVA (carbon) – Lose 4 e / Gain 4 e VA (Nitrogen) – Gain 3 e VIA (oxygen) – Gain 2 e Halogen – Gain 1 e Noble Gases - neutral Ionic Charges

17. Electrons in an neutral atom What must be true of (p+) and (e-) if an atom has neutral charge? The atomic number is the number of protons (p+) in an atom

18. What do the numbers mean? Atomic Number Atomic Symbol Atomic Mass On your table this may be different!

19. Fill in the following periodic table with the total number of electrons in a neutral species of the atom

20. e- e- e- Valence Electrons • The number of electrons in the outer “shell” are known as valence electrons. • Use Bohr’s Model to picture this concept First shell: Second Shell: Third shell: 2 8 Question: How many electrons fit in a shell? 18

21. Valence Electrons 1 2 The number of electrons in the outer shell of an atom 1 2 3 4 5 6 7 8 2 2 2 2 2 2 2 2 2 3 4 5 6 7 8 1 8 8 8 8 8 8 8 8 2 2 2 2 2 2 2 2