1. Chemistry Comes Alive: Part A2
Chemistry Comes Alive: Part A

2. Anything that has mass and occupies space States of matter:
Solid—definite shape and volume
Liquid—definite volume, changeable shape
Gas—changeable shape and volume

3. Energy Capacity to do work Types of energy: Kinetic—energy of motion
Potential—stored energy
PLAY
Animation: Energy Concepts

4. Forms of Energy
Chemical energy—stored in bonds of chemical substances
Electrical energy—results from movement of charged particles
Mechanical energy—directly involved in moving matter
Radiant or electromagnetic energy—exhibits wavelike properties (i.e., visible light, ultraviolet light, and X-rays)

5. Major Elements of the Human Body
Oxygen (O)
Carbon (C)
Hydrogen (H)
Nitrogen (N)
About 96% of body mass

6. Lesser Elements of the Human Body
About 3.9% of body mass:
Calcium (Ca), phosphorus (P), potassium (K), sulfur (S), sodium (Na), chlorine (Cl), magnesium (Mg), iodine (I), and iron (Fe)

7. Atomic Structure Neutrons Protons Electrons No charge Positive charge
Negative charge

8. Nucleus Nucleus Helium atom Helium atom 2 protons (p+) 2 neutrons (n0)
2 electrons (e–)
2 protons (p+)
2 neutrons (n0)
2 electrons (e–)
(a) Planetary model
(b) Orbital model
Proton
Neutron
Electron
Electron
cloud
Figure 2.1

9. Identifying Elements
Atoms of different elements contain different numbers of subatomic particles
Compare hydrogen, helium and lithium (next slide)

10. Hydrogen (H) (1p+; 0n0; 1e–) Helium (He) (2p+; 2n0; 2e–) Lithium (Li)
Proton
Neutron
Electron
Hydrogen (H)
(1p+; 0n0; 1e–)
Helium (He)
(2p+; 2n0; 2e–)
Lithium (Li)
(3p+; 4n0; 3e–)
Figure 2.2

11. Atomic number = number of protons in nucleus
Identifying Elements
Atomic number = number of protons in nucleus
Mass number = mass of the protons and neutrons
Isotopes are structural variations of elements that differ in the number of neutrons they contain but always have the same number of protons.

12. Hydrogen (1H) (1p+; 0n0; 1e–) Deuterium (2H) (1p+; 1n0; 1e–)
Proton
Neutron
Electron
Hydrogen (1H)
(1p+; 0n0; 1e–)
Deuterium (2H)
(1p+; 1n0; 1e–)
Tritium (3H)
(1p+; 2n0; 1e–)
Figure 2.3

13. Molecules and Compounds
Most atoms combine chemically with other atoms to form molecules and compounds
Molecule—two or more atoms bonded together (e.g., H2 or C6H12O6)
Compound—two or more different kinds of atoms bonded together (e.g., C6H12O6)

14. Chemical Bonds
Electrons occupy up to seven electron shells (energy levels) around nucleus
Octet rule: Except for the first shell which is full with two electrons, atoms interact in a manner to have eight electrons in their outermost energy level (valence shell)

15. Chemically Inert Elements
Stable and unreactive
Outermost energy level fully occupied or contains eight electrons

16. (a) Chemically inert elements
Outermost energy level (valence shell) complete 8e 2e 2e
Helium (He)
(2p+; 2n0; 2e–)
Neon (Ne)
(10p+; 10n0; 10e–)
Figure 2.5a

17. Chemically Reactive Elements
Outermost energy level not fully occupied by electrons
Tend to gain, lose, or share electrons (form bonds) with other atoms to achieve stability

18. (b) Chemically reactive elements
Outermost energy level (valence shell) incomplete 4e 1e 2e
Hydrogen (H)
(1p+; 0n0; 1e–)
Carbon (C)
(6p+; 6n0; 6e–) 1e 6e 8e 2e 2e
Oxygen (O)
(8p+; 8n0; 8e–)
Sodium (Na)
(11p+; 12n0; 11e–)
Figure 2.5b

19. Types of Chemical Bonds
Ionic
Covalent

20. Ions are formed by transfer of valence shell electrons between atoms
Ionic Bonds
Ions are formed by transfer of valence shell electrons between atoms
Anions (– charge) have gained one or more electrons
Cations (+ charge) have lost one or more electrons
Attraction of opposite charges results in an ionic bond

21. + – Figure 2.6a-b Sodium atom (Na) (11p+; 12n0; 11e–)
Chlorine atom (Cl)
(17p+; 18n0; 17e–)
Sodium ion (Na+)
Chloride ion (Cl–)
Sodium chloride (NaCl)
(a) Sodium gains stability by losing one electron, and
chlorine becomes stable by gaining one electron.
(b) After electron transfer, the oppositely
charged ions formed attract each other.
Figure 2.6a-b

22. (c) Large numbers of Na+ and Cl– ions
CI–
Na+
(c) Large numbers of Na+ and Cl– ions
associate to form salt (NaCl) crystals.
Figure 2.6c

23. Covalent Bonds
Formed by sharing of two or more valence shell electrons
Allows each atom to fill its valence shell at least part of the time

24. + Reacting atoms Resulting molecules or Structural formula shows
single
bonds.
Hydrogen
atoms
Carbon
atom
Molecule of
methane gas (CH4)
(a) Formation of four single covalent bonds:
carbon shares four electron pairs with four
hydrogen atoms.
Figure 2.7a

25. Occur when chemical bonds are formed, rearranged, or broken
Chemical Reactions
Occur when chemical bonds are formed, rearranged, or broken
Represented as chemical equations
Chemical equations contain:
Molecular formula for each reactant and product
Relative amounts of reactants and products, which should balance

26. Examples of Chemical Equations
H + H  H2 (hydrogen gas)
4H + C  CH4 (methane)
(reactants)
(product)

27. Rate of Chemical Reactions
Rate of reaction is influenced by:
 temperature   rate
 particle size   rate
 concentration of reactant   rate
Catalysts:  rate without being chemically changed
Enzymes are biological catalysts