1. 2.1 – Atoms, Ions, and Molecules

2. Do Now:  In terms of chemistry, what do a frog, a skyscraper, and your body all have in common?

4. Atoms  Atom- smallest basic unit of matter It would take more than 1 trillion years to count the atoms in a single grain of sand H O Hydrogen atom (H) Oxygen atom (O)

5. Subatomic Particles  Atoms are made up of 3 smaller parts: 1. Protons (+) – Found in nucleus 2. Neutrons (0) – Found in nucleus 3. Electrons (-) – Energy levels outside of nucleus Oxygen atom (O) Nucleus: 8 protons (+) 8 neutrons outermost energy level: 6 electrons (-) inner energy level: 2 electrons (-)

6. Elements Element- one particular type of atom, cannot be broken down If all elements are made up of atoms… what distinguishes between elements?

7. Reading the periodic table:

8. Elements in living things  “CHNOPS”  Carbon, Hydrogen, Oxyen, and Nitrogen make up about 95% of our body  Sulfur is needed for proteins  Phosphorous is needed for DNA You must memorize these!!!!!

9. Compound  Compound- a substance made of atoms of different elements bonded together in a certain ratio  A compound has different properties than the elements that it is made of  What type of chemical compounds have we talked about so far this year? O HH _ ++

10.  Carbon Dioxide

11. Example:  Hydrogen and Oxygen are both found as gases naturally on earth  BUT… when combined they can form water  A diamond is pure carbon but carbon atoms are also found in sugar, protein, and millions of other compounds.

12. Bohr Models  Niels Bohr, 1913  Showed a positively charged nucleus surrounded by negatively charged electrons  Useful for showing bonds in chemical compounds See handout for rules!

13. Practice:  In your notes, draw the correct Bohr diagram for:  Carbon (C) Atomic number = 6 Mass = 12  Sodium (Na) Atomic number = 11 Mass = 22

14. Quick review:  How are elements different from compounds?  Give at least 2 reasons:

15. Ions form when atoms gain or lose electrons.  An ion is an atom that has gained or lost one or more electrons.  positive ions  negative ions Ionic bonds form between oppositely charged ions. They are held together by electrical force! Easily dissolve in water! Sodium atom (Na)Chlorine atom (CI)Sodium ion (Na + )Chloride ion (CI - ) Na loses an electron to CI ionic bond gained electron

16. Ionic Bond Example:

17. How do we know if an atom wants to gain or lose electrons?  The atom wants a full energy level by moving the LEAST amount of electrons  So…  If it has 3 or less electrons it will give electrons away and become POSITIVELY charged  If it has 5 or more electrons it will gain more electrons and become NEGATIVELY charged

18. Atoms share pairs of electrons in covalent bonds.  A covalent bond forms when atoms share a pair of electrons.  Usually very strong! covalent bonds Oxygen atom (O)Carbon atom (C)Oxygen atom (O) Carbon dioxide (CO 2 ) –multiple covalent bonds –diatomic molecules –Ex: O 2

19. Molecules  Molecule- two or more atoms held together by covalent bonds

20. One last type of bonding – Dipole-Dipole  Due to the unequal sharing of electrons, some molecules have a slightly positive and a slightly negative end to them, or a dipole (di-pole = two magnetic poles)  These compounds can form weak bonds with one another without combining together completely to create new compounds  Ex: Water hydrogen bonds  Van Der Waals forces

21. Isotopes Isotope: An atom that contains a larger or smaller number of neutrons than usual -similar chemical properties -still no charge

22. Student ntoes

23. 2.1 – Atoms, Ions, and Molecules

24. Atoms  Atom- ______________________________ It would take more than 1 trillion years to count the atoms in a single grain of sand H O

25. ______________ Particles  Atoms are made up of 3 smaller parts: 1. _____________(+) – Found in ______________ 2. ____________(0) – Found in _______________ 3. ______________(-) – Energy levels outside of nucleus Oxygen atom (O) Nucleus: 8 protons (+) 8 neutrons outermost energy level: 6 electrons (-) inner energy level: 2 electrons (-)

26. ____________________ Element- one ____________________________, cannot be broken down If all elements are made up of atoms… what distinguishes between elements?

27. Reading the periodic table:

28. Elements in living things  “___________________”  ____________, ______________, ___________, and ____________make up about 95% of our body  Sulfur is needed for proteins  Phosphorous is needed for DNA You must memorize these!!!!!

29. __________________  Compound- a substance made of ____________________________________ ____________________________________  A compound has _______________________than the elements that it is made of  What type of chemical compounds have we talked about so far this year? O HH _ ++

30. Example:  Hydrogen and Oxygen are both found as gases naturally on earth  BUT… when combined they can form water  A diamond is pure carbon but carbon atoms are also found in sugar, protein, and millions of other compounds.

31. Quick review:  How are elements different from compounds?  Give at least 2 reasons:

32. Ions form when atoms _____________________________  An _________________is an atom that has gained or lost one or more electrons.  _______________ions  ________________ions ______________________form between oppositely charged ions. They are held together by electrical force! ______________________________! Sodium atom (Na)Chlorine atom (CI)Sodium ion (Na + )Chloride ion (CI - ) Na loses an electron to CI ionic bond gained electron

33. Ionic Bond Example:

34. How do we know if an atom wants to gain or lose electrons?  The atom wants _______________________ by moving the ___________amount of electrons  So…  If it has 3 or less electrons it will give electrons away and become POSITIVELY charged  If it has 5 or more electrons it will gain more electrons and become NEGATIVELY charged

35. Atoms share pairs of electrons in covalent bonds.  A ________________________ forms when atoms share a pair of electrons.  Usually __________________! covalent bonds Oxygen atom (O)Carbon atom (C)Oxygen atom (O) Carbon dioxide (CO 2 ) –multiple covalent bonds –diatomic molecules –Ex: O 2

36. Molecules  __________________- two or more atoms held together by _____________________