1. Electron Arrangement

2. Electrons are arranged in energy levels around the nucleus Electrons are arranged in energy levels around the nucleus Each energy level can only hold a limited number of electrons Each energy level can only hold a limited number of electrons An atom will always fill the innermost energy level before placing the e - in the next energy level An atom will always fill the innermost energy level before placing the e - in the next energy level (under normal conditions)

3. 1 st energy level can hold up to 2 e - 2 nd & 3 rd and so on can hold up to 8 e -

4. Valence Electrons The e- in the outer most level The e- in the outer most level They are important because they determine HOW an atom acts towards other atoms They are important because they determine HOW an atom acts towards other atoms They tell us the number of electrons that will take place in bonding with other atoms They tell us the number of electrons that will take place in bonding with other atoms

5. Chemical Bonding

6. Bonding Compounds are held together by electrostatic attraction between + and - charged atoms All atoms like to be….. HAPPY

7. What is a happy atom? Any atom with a full VALENCE energy shell Any atom with a full VALENCE energy shell Is this atom happy? ?

8. Not only do they like to be happy Atoms are also….. LAZY Example: If an atom has 1e in the outer shell, is it easier to FIND 7e to make it full or is it easier to LOSE 1e to make the previous energy level the outer shell?

9. If an atom has 3e in the outer shell, is it easier to FIND 5e to make it full or is it easier to LOSE 3e to make the previous energy level the outer shell?

10. Ionic Bonds: Atoms will fill their outer level by transfer of their e - So……the loss or gain of an electron causes an unbalanced charge Atoms of unlike charges attract

11. Ionic bond

12. Ionic bonds are between Metals + Non-metals

13. Covalent Bonds: Atoms will share outer most e- to fill each atoms outermost energy level

14. If covalent bonds are not shared equally, it is called a polar covalent bond

15. Covalent bonds are between Non-metals + Non-metals

16. Practice….. When an atom gives up 1 or more electrons, what type of bond is it? IONIC When an atom shares electrons, what type of bond is it? COVALENT

17. Ions If an atom is NOT electrically neutral and has a positive or negative charge it is called an ION If an atom is NOT electrically neutral and has a positive or negative charge it is called an ION A positively charged ion is called CATION A positively charged ion is called CATION A negatively charged ion is called an ANION A negatively charged ion is called an ANION

19. Ways to write atoms/molecules e- dot formula – shows valence e- only e- dot formula – shows valence e- only Bohr formula – represents where all atomic particles are in the atom Bohr formula – represents where all atomic particles are in the atom Chemical formula – number and kinds of atoms present Chemical formula – number and kinds of atoms present Structural formula – number, kinds and arrangement with bonds Structural formula – number, kinds and arrangement with bonds