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Atomic bonding

Atomic bonding . Why and How A toms Combine Lewis Dot Diagrams. Lewis diagrams . When atoms combine, only electrons in the outer (valence) shell are involved. We can represent these valence electrons with Lewis diagrams.

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Atomic bonding

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  1. Atomic bonding Why and How Atoms Combine Lewis Dot Diagrams

  2. Lewis diagrams • When atoms combine, only electrons in the outer (valence) shell are involved. We can represent these valence electrons with Lewis diagrams. • On the next slide there is a diagram of the first 20 elements and their dot configuration: • We will only be worrying about these elements for now.

  3. Here are the steps for writing Lewis Diagrams: • Write the element symbol. • Around this draw dots (One for each valence electron) • The dots should be spread over four sides. (Dots are not paired until all sides have at least one dot) • Lewis Dot Table

  4. It doesn’t matter what side the dots are placed for example hydrogen can be written 4 different ways:

  5. Check this out: • The number of valence electrons is equal to the group number. • For example, hydrogen is in group IA (group 1) and it has one valence electron. Neon is in 0 (group 8) and it has 8 valence electrons. • The only exception is He which is in group 8 but has 2 valence electrons. • Lewis Dot Table

  6. Lets practice one together: • What would the Lewis Dot Diagram be for Ne? • Lets write down the symbol • Now how many valence electrons does it have? • Draw a dot for each valence electron

  7. Lets do a few more:

  8. Does yours look like this?

  9. So how do we use this? • The Octet Rule: • When atoms form ions or combine in compounds they obtain electron configurations of the nearest noble gas (usually this means that there will be 8 outer electrons). • Nearest refers to the number of representative elements between an element and a noble gas.

  10. Here are the noble gasses:

  11. For example: • Br is 1 space removed from Kr, but 7 spaces removed from Ar (see your periodic table). • Therefore: Br would gain 1 electron to form Br–. • Similarly, Mg would lose 2 electrons to become Mg2+.

  12. Class practice:

  13. Types of bonds: • Ionic: occurs between metals and non-metals • Covalent: occurs between two non-metals • Alloys: we aren't worried about these at the moment

  14. Here are two examples:

  15. Which are metal and non metal?

  16. Tomorrow: • We will use the Lewis dot diagrams to display: • Ions • Ionic bonding • Covalent Bonding

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