1. Ch.2-1
Nature of Matter
Chemistry of life

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. POINT > Describe atoms, elements and isotopes
Atoms are the basic unit of matter
Protons –
Neutrons –
Electrons –
Positively charged particles (+)
Nucleus
(Center of an atom)
Particles with no charge
Negatively charged particles (-)

4. POINT > Describe atoms, elements and isotopes
An element is a pure substance consisting of only one type of atom Ex. Hydrogen, carbon, nitrogen, oxygen, etc

5. POINT > Describe atoms, elements and isotopes

6. POINT > Describe atoms, elements and isotopes
An element’s identity is determined by the number of protons (Atomic number)
Hydrogen – 1 proton
Carbon – 6 protons
Nitrogen – 7 protons
Oxygen – 8 protons
Sulfur – 16 protons

7. POINT > Describe atoms, elements and isotopes
Carbon-12
Carbon-13
Carbon-14
Isotopes are atoms of a single element that differ in the number of neutrons
Same # electrons and protons = Same chemical properties

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

9. POINT > Define compound, ionic and covalent bonds
A compound is a substance made of two or more elements chemically bound together Ex. Water H2O > 2 hydrogen, 1 oxygen A molecule is the smallest unit of most compounds

10. POINT > Define compound, ionic and covalent bonds
An ion is a charged atom. Ions are formed when an atom gains or loses an electron(s) An atom that loses electrons has a positive charge An atom that gains electrons has a negative charge Positive and negative ions are attracted to each other

11. POINT > Define compound, ionic and covalent bonds
An ionic bond is formed between a positive ion and a negative ion (opposite charges attract). Ionic bonds are relatively strong + -

12. POINT > Define compound, ionic and covalent bonds
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. POINT > Identify water as a polar molecule
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 :
What makes water a “polar” molecule?
Which atom in a water molecule has a slight negative charge?

16. POINT > Describe hydrogen bonding
Hydrogen bonds are formed by attraction between the slight (+) on one water molecule and the slight (-) charge on another water molecule

17. POINT > Describe hydrogen bonding
Hydrogen bonds are much weaker than ionic or covalent bonds

18. POINT > Identify properties of water
Hydrogen bonding gives water some unique characteristics:
1. Cohesion is the attraction between molecules of the same substance (water)
So water forms beads on smooth surfaces, and has surface tension

19. POINT > Identify properties of water
2. Adhesion is the attraction between molecules of different substances
This causes a meniscus in a graduated cylinder

20. POINT > Identify properties of water
3. Heat capacity: Water can absorb lots of heat with only a small change in temperature This is important for homeostasis! (cooling) 4. Water is an excellent solvent. Many things will dissolve in water because of its polar nature This allows chemical reactions to occur in cells!

21. 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?
Which are stronger, hydrogen bonds or ionic bonds?

22. Homework: Read pages 34-44 p. 38 #1-5 P. 44 #1-2 Complete answers
Homework: Read pages p.38 #1-5 P.44 #1-2 Complete answers! Due Wednesday