1. Warm Up Four elements make up 96% of the human body. Name another example of something that is complex, yet made up of very simple units:

2. Chemistry of Life

3. Objective Checklist Compare and contrast molecules and compounds Compare and contrast covalent and ionic bonds Use the periodic table to conclude electron configurations Predict bonding patterns based on electronegativity

4. “It would take you more than 1 trillion years to count the number of atoms in one grain of sand.”

5. An element is a pure substance that cannot be separated into simpler substances An atom is the smallest particle of an element that retains all the properties of that element A molecule is composed of more than one atoms bonded together A compound is made up of atoms of two or more different elements that are bonded together

6. An Analogy… Imagine going to an ice cream store. Let's say that they have 30 different flavors of ice cream. The smallest amount of ice cream that the store will sell to you is a scoop. If you want, you can put two or more scoops of the same flavor of ice cream together; or, you can put two or more scoops of different flavors of ice cream together.

7. An Analogy… Use an ice cream shop to prepare an analogy of the following: –Element –Atom –Molecule –Compound = flavor = one scoop of a certain flavor = 2 scoops, any flavor = 2 scoops, different flavors

8. An Analogy… Describe with your own analogy in terms of the following: –Element –Atom –Molecule –Compound

9. The Atom: PARTICLEMASSCHARGE ELECTRONVirtually noneNegative PROTON1 AMUPositive NEUTRON1 AMU (slightly more massive than proton) Neutral

10. The Atom:

11. Periodic Table of Elements Atomic Number = Number of Protons

12. Electron Locations Electrons fill energy levels surrounding an atom’s nucleus The electrons found on the outer energy levels are called valence electrons An atom is most stable when its outermost energy level is “full” –1 st energy level can have up to 2 electrons –All following energy levels can have up to 8 electrons (this might be different to what you have learned in physical science)

13. Electron Locations Carbon (6 protons)

14. Electron Locations Hydrogen (1 proton)

15. Electron Locations Oxygen (8 protons)

16. Ions Ions form because atoms are more stable when their outermost energy level is full To achieve this, they may lose or gain electrons When they do this, they become charged (positive charge = cation; negative charge = anion) Anions and cations tend to attract each other, forming ionic bonds

17. Na Cl + -

18. Covalent Bonds Another way atoms can achieve a full outermost shell is by SHARING electrons Single bonds – one electron pair is shared

19. Double Covalent Bonds Double bonds – two electron pairs are shared

20. Double Covalent Bonds

21. Predicting Bonding & Polarity Noble gasses have full valence energy levels so they do not bond with other elements

22. Predicting Bonding & Polarity These are missing one valence electron, so tend to “steal” electrons from other elements, making them anions

23. Predicting Bonding & Polarity These only have 1 valence electron, so they tend to lose those electrons, making them cations

24. Predicting Bonding & Polarity Anions and cations tend to attract each other forming ionic compounds Ex: NaCl (Sodium Chloride)

25. Predicting Bonding & Polarity Non Metals can share electrons with each other (form covalent bonds) to form molecules

26. Predicting Bonding & Polarity Electronegativity is the attraction an atom has for electrons It increases as you move RIGHT and UPWARDS on the periodic table

27. Predicting Bonding & Polarity Fluorine is the most electronegative atom, meaning it has the strongest attraction for electrons

28. Compare and contrast molecules and compounds Compare and contrast covalent and ionic bonds Use the periodic table to conclude electron configurations Predict bonding patterns based on electronegativity Objective Checklist

29. Questions, Comments? Video: Meet the Elements Video: Meet the Elements