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Chemistry of Cells 3-1

Chemistry of Cells 3-1. Atoms. make up all living and non-living things smallest unit that can't be broken down by chemical means every atom has a nucleus, electrons (e-), protons (p+), and neutrons (n). Elements. when a substance is made of only one kind of atom

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Chemistry of Cells 3-1

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  1. Chemistry of Cells 3-1

  2. Atoms • make up all living and non-living things • smallest unit that can't be broken down by chemical means • every atom has a nucleus, electrons (e-), protons (p+), and neutrons (n)

  3. Elements • when a substance is made of only one kind of atom • cannot be broken down into any other substance • Ex: Au -- atoms are all Au • Periodic table outlines known elements

  4. Ions • particles with unequal # of p+ and e-

  5. Electrons • e- organized outside the nucleus by amount of energy they possess • e- close to nucleus = low energy • e- far from nucleus = high energy

  6. Isotopes • atoms of the same element that have a different number of neutrons

  7. Compound • substance formed by 2 or more elements in definite proportions • written as formulas: • NaCl = sodium chloride (salt) • H2O = water • HCl = hydrochloric acid • CO2 = carbon dioxide

  8. Chemical Bonds • Covalent bonds • 2 atoms that share e- • group of atoms held together with a covalent bond called a molecule • Very strong bond, formed between 2 or more specific atoms sharing e-

  9. Chemical Bonds • Ionic bonds • form between 2 atoms of opposite charge • exchange of e- occurs to form the ions that form the ionic bond • Force of attraction btwn a (+) and (-) ion is the ionic bond • Will break apart in water and produce free ions

  10. Chemical Bonds • Hydrogen • weak bond that links molecules • forms btwn 2 polar molecules (have unequal areas of charge) • Ex: H2O -- the shared e- here are more attracted to the O than the H • Bond structure determines the shape of DNA and proteins

  11. Water in Cells: 3-2

  12. Properties of water • 1.) Stores heat -- helps cool us down when we sweat • 2.) Clings to itself - Cohesion • causes water to be liquid at room temperature • has a surface tension

  13. Properties of water • 3) Adhesion - attraction of water to another substance • water adheres to anything it can form a hydrogen bond 4) Capillary Action - water adheres to a substance with a surface charge

  14. Properties of water • 5) Water ionizes! - covalent bonds of water break down into OH- + H+ • 6) Good solvent - dissolves solutes (Ex: sugar) into a solution --- molecules evenly distributed

  15. Definitions • Solute - substance that is dissolved • Solvent - substance in which the solute is dissolved • Solution - mix of solvent and solute • Suspension - mix of water and non-dissolved material Ex: sugar cube in water

  16. Acids and Bases • Acid - forms H+ in water (donates a proton) • Base - forms OH- in water (accepts a proton) • pH scale - tells how much H+ ion you have in soln. • 1 7 14 • Buffer - weak acids or bases that react with strong acids and bases to prevent sharp pH changes.

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