1. Ch.2-1 Nature of Matter

2. POINT > Describe atoms, elements and isotopes POINT > Define compound, ionic and covalent bonds POINT > Identify water as a polar molecule POINT > Describe hydrogen bonding POINT > Identify properties of water

3. What are the basic chemical principles that affect living things?

4. Atoms are the basic unit of matter  Protons –  Neutron –  Electron – Nucleus (Center of an atom) Positively charged particle (+) Particles with no charge Negatively charged particle (-)

5. An element is a pure substance consisting of only one type of atom Ex. Hydrogen, Carbon, Nitrogen, Oxygen, etc

7. An element’s identity is determined by the number of protons (Atomic Number)  Hydrogen – 1  Carbon – 6  Nitrogen – 7  Oxygen – 8  Sulfur – 16

8. Isotopes are atoms of the same element that differ in the number of neutrons Same # electrons = Same chemical properties Carbon-12Carbon-13Carbon-14

9. WB CHECK : Give three examples of elements. What are isotopes?

10. A compound is a substance made of two or more atoms chemically bound together Ex. Water – A molecule is the smallest unit of most compounds H 2 O  2 hydrogen, 1 oxygen

11. An ion is a charged atom. Ions are formed when one or more electrons are transferred from one atom to another An ionic bond is formed between a positive ion and a negative ion (opposite charges attract). Ionic bonds are relatively strong.

12. A covalent bond is formed when one or more electrons are shared between two atoms. Covalent bonds are even stronger than ionic bonds

13. WB CHECK : What is added or removed from an atom to make an ion? What holds an ionic bond together? What holds a covalent bond together? Which are stronger, covalent or ionic bonds?

14. The oxygen and hydrogen atoms in water share electrons (covalent bonds), but not equally Water has an uneven distribution of electrons (Partial (-) at oxygen end, (+) at hydrogen end) This makes water a polar molecule

15. WB CHECK : Why is water a “polar” molecule?

16. Hydrogen bonds are formed by attraction between hydrogen atom with slight (+) on one water molecule and an oxygen atom with slight (-) charge on another water molecule Hydrogen bonds are weak compared to ionic or covalent bonds

17. Hydrogen bonding gives water some unique characteristics Cohesion is the attraction between molecules of the same substance (water forms beads on smooth surfaces, and has surface tension)

18. Adhesion is the attraction between molecules of different substances (causes meniscus in graduated cylinder)

19. Heat Capacity: Water can absorb lots of heat with only a small change in temperature This is important for homeostasis! (cooling) Water is an excellent solvent. Many things will dissolve in water because of its polar nature. This allows chemical reactions to occur in cells!

20. WB CHECK : Which property of water causes it to form drops? Which property of water allows drops to stick to a window? Which property of water makes it useful for body temperature control?

21.  Read pages 34-44  p.38#1-5  P.44 #1-2 Complete answers! Due Wednesday