Exploring Chemistry of Life: Matter, Elements, Atoms, and Reactions

1. Chemistry of Life Honors Biology: Chapter 2

2. Matter • Everything in the universe is made up of matter. • Matter- anything occupying space and has mass. • Mass- amount of matter an object has. • Weight- force of gravity on a given mass. Q: Would your weight or mass change if you went to the moon?

3. Elements and Atoms • Elements- pure substances that cannot be broken down chemically into simpler kinds of matter. • 100+ elements have been discovered. • Less than 30 are important to living things. • Over 90% of the mass of living things consists of: • Carbon (C) • Hydrogen (H) • Oxygen (O) • Nitrogen (N)

4. Elements and Atoms • Periodic Table of Elements- lists information about each element including the element’s • Chemical symbol- 1-3 letters • Atomic number • Atomic mass

5. Elements and Atoms • Atom- simplest particle of an element that retains all of the properties of that element. Nucleus

6. Elements and Atoms • 3 Subatomic Particles in Atoms • Proton- Positively charged particle found in the atom’s nucleus. ATOMS OF AN ELEMENT ALWAYS HAVE THE SAME NUMBER OF PROTONS. • Neutron- Found within the nucleus and has no charge. • Electron- Small negatively charged particles with very little mass. • Move in orbitals found outside of the nucleus.

7. Elements and Atoms • Nucleus • Most of the atom’s mass • Contains protons and neutrons • Atomic Number = # of protons • Mass Number = # of protons + # of neutrons Q: How can you determine the number of neutrons an atom has? A: Mass number – Atomic number = # of neutrons

8. Elements and Atoms • Atoms have a net charge of ZERO. • # of Protons (+) = # of electrons (-) • Orbital- 3D region around the nucleus indicating the probable location of an electron. • Combination of all orbitals electron cloud • Farther from nucleus  greater electron’s energy

9. Elements and Atoms • Orbitals and energy levels: • Each energy level corresponds to certain orbitals that can hold a set number of electrons. • First energy level has 1 orbital- holds maximum of 2 • Second energy level has 4 orbitals that hold 2 electrons each (total of 8).

10. Elements and Atoms • Isotopes- Atoms of the same element that have a different number of neutrons (number of protons DOES NOT change). • Changes atomic mass

11. Carbon Isotopes

12. Compounds • http://gtm-media.discoveryeducation.com/videos/Discovering the Elements/sec2941_300k.asf

14. Compounds • Atoms of most elements readily combine with the same/different atoms or elements to make compounds. • Compound- atoms of 2+ elements in fixed proportions. • Ex: Water (H2O)

15. Compounds • Chemical and physical properties differ between compounds and the elements making them up. • Number and arrangement of e- determines how elements combine and form compounds. • Atoms are stable/less reactive when highest energy level is full. Ex: Noble gases

16. Chemical Bonds • Attractive forces holding atoms together. • Covalent Bond • Ionic Bond • Hydrogen bond

17. Covalent Bond • Formed when 2 atoms SHARE 1+ pairs of valence electrons.

18. Ionic Bonds • Transfer of e- from a metal atom to a nonmetal atom. • More stability for the atoms involved. • Creates ions (charged atoms that have gained/lost e-)

19. ??Element or Compound?? • HCl • CO2 • Cl • Li • H2O HCl, CO2, and H2O- compounds Cl and Li- elements

20. Energy

21. Energy and Matter • Energy- the ability to do work. • Forms of energy include: • Radiant (light) energy • Thermal (heat) energy • Chemical energy • Electrical energy • Mechanical energy

22. States of Matter • All atoms and molecules in a substance are in constant motion. • Motion of and spacing between atoms/molecules determine the substances state: • Solid • Liquid • Gas

23. Solids • Move less rapidly than liquids or gases • Fixed volume • Molecules/atoms more closely linked than liquids or gases (with the exception of H2O).

24. Liquid • Maintain a fixed volume, but particles move more freely  ability to flow and conform to container’s shape.

25. Gas • Particles move rapidly • Little to no attraction to each other. • Fill the volume of the container they occupy.

26. Energy and Chemical Reactions • Chemical Reaction- change from one substance to another. • Energy is absorbed/released when bonds are broken and new bonds are formed. • Ex: CO2 + H2O  H2CO3 (see pg 36 Fig 2-6) Q: Where are the reactants? Products? Q: What does the arrow represent?

27. Energy and Chemical Reactions • Reactants  Products • Products  Reactants • Number of each type of atom must be EQUAL on both sides of the equation. • Reversible reactions shown using arrows pointing in both directions.

28. Where Do You Get Your Energy?? • Sugars, proteins, and fats in your food get broken down into CO2, H2O, and other products. • Breaking bonds  release of energy to be used in building & maintaining cells, tissues, and organs.

29. Starting Reactions • Activation energy- amount of energy needed to start a reaction. • Usually a large amount of energy is needed to start reactions. • Catalysts- reduce the activation energy needed for a reaction without being changed/destroyed. • Enzymes- “special” proteins • RNA molecules

30. Activation Energy

31. Oxidation-Reduction Reactions • Oxidation-reduction reaction = redox • Oxidation reaction: reactant loses 1+ electrons  more + charge • Reduction reaction: reactant gains 1+ electrons  more – charge • Oxidation reactions are always followed by a reduction reaction.

32. Redox Reactions • Forming Na+ Cl- involves oxidation and reduction reactions. • Na donates an e- to Cl oxidation of Na to form Na+ • Cl accepts an e-  reduction of Cl to form Cl-

33. Enzymes • Type of protein. • Most enzyme reactions are reversible (arrow goes both ways). • Maintain homeostasis: reactions would not occur fast enough without them. • “–ase” = enzyme • ONLY react with specific substrates.

34. Enzymes

35. THE END!