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Atomic Structure. Key 11 Na Sodium 22.99 Atomic Number Element symbol Element name Average atomic mass*

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Presentation on theme: "Atomic Structure. Key 11 Na Sodium 22.99 Atomic Number Element symbol Element name Average atomic mass*"— Presentation transcript:

1 Atomic Structure

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4 Key 11 Na Sodium Atomic Number Element symbol Element name Average atomic mass*

5 Key 11 Na Sodium Atomic Number Number of Protons Number of Electrons (when atom is neutrally charged) Property unique to each element

6 Key 11 Na Sodium Element symbol Sometimes abbreviation of English name Sometimes abbreviation of Latin/Greek name Familiarize yourself with them and Chemistry problems will become easier

7 Key 11 Na Sodium Element name What we call it

8 Key Average atomic mass* Weighted Average number of Protons and Neutrons (approximately) Na Sodium

9 Subatomic Particles the particles that make up an atom Protons – high mass, positive charge. Found in nucleus. Neutrons – high mass, no charge. Found in nucleus. Electrons – low mass, negative charge. Found orbiting around nucleus. (abbreviated e – )

10 Basic Electrical Charge Laws + and – : Attract (pull together) – and – : Repel (push away) + and + : Repel (push away) Like charges repel and Opposites attract

11 An Atom Nucleus 1 proton = H = hydrogen

12 Why doesn’t the electron fall into the nucleus? It orbits because the electron is moving really fast around the nucleus. Because the electron has such a low mass, even a small amount of energy makes it move very fast.

13 An Atom Nucleus 1 proton = H = hydrogen

14 Another Atom Size of atom Size of nucleus 2 protons = He = helium

15 Zooming Out – Another Atom 3 protons = Li = lithium

16 Yet Another Atom 4 protons = Be = beryllium

17 5 protons = B = boron

18 6 protons = C = carbon

19 Valence Electrons valence electrons – the outermost electrons. (only the electrons in the last s and p orbitals). Only the electrons in the outermost energy levels are available for bonding.

20 Valence Electrons How many electrons in the valence shell of a carbon atom?

21 6 protons = C = carbon Inner electrons = 2 e – not available for bonding Outer electrons = 4 e – available for bonding

22 4 electrons in valence shell

23 How many e – in valence shell?

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31 Lewis Dot Structures Lewis dot structures are a convenient way to show how many valence electrons an atom has. Example: Draw the Lewis dot structure for hydrogen. H

32 Lewis Dot Structures  Write the symbol for the element.  Look for the “A” number at the top of the element’s column (e.g. 5A). This is the number of valence electrons.  Draw that many dots around the symbol. Draw at most 2 dots on each side (top, bottom, left, right)  The maximum number of dots is 8.  Exception: Helium only has 2 dots. He Ne

33 More Lewis Structure Practice  Draw the Lewis structure for oxygen.  Draw the Lewis structure for magnesium.  Draw the Lewis structure for chlorine. O Mg Cl

34 Even More Lewis Structure Practice  Draw the Lewis structure for carbon.  Draw the Lewis structure for potassium.  Draw the Lewis structure for phosphorus. C K P

35 Ne F ONC B Be He Li H KrAr Cl Br Xe ISPSi Mg Al Ca Na K

36 4 e – in valence shell

37 Valence Shell Only the electrons in the outermost energy levels are available for bonding. valence shell – the outermost bundle of energy levels.


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