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Chapter 4

Chapter 4. The Chemical Basis of Life. Matter. All living things are made up of matter – anything that has mass and takes up space Water, air, and your body are different substances but are all made up of matter. NOT IN PACKET. MATTER – solid, liquid, gas, plasma MOLECULES ATOMS

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Chapter 4

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  1. Chapter 4 The Chemical Basis of Life

  2. Matter • All living things are made up of matter– anything that has mass and takes up space • Water, air, and your body are different substances but are all made up of matter

  3. NOT IN PACKET • MATTER – solid, liquid, gas, plasma • MOLECULES • ATOMS • SUBATOMIC PARTICLES • Protons • Electrons • Neutrons

  4. Mass vs Weight • Mass– the amount of matter an object has • Weight – the amount of mass an object has plus the force of gravity

  5. States of Matter • Matter exists in 4 different states • Solid – definite shape and volume

  6. Liquid– definite volume, not shape • Gas – no definite shape or volume

  7. Plasma - high temperature ionized gas

  8. Elements • Element – substance made up of the same type of atoms that can not be broken down chemically into a simpler kind of matter

  9. 25 elements are important to living things • 4 make up 96% of the living matter in your body • Oxygen, Carbon, Hydrogen, Nitrogen

  10. Trace elements – elements that make up less than .01 percent of body mass, but critical to health • Ex. 1.5 mg of Iodine each day – affects thyroid gland • .004% Iron – important for O2 in your blood

  11. Compounds • Compound – substance containing 2 or more elements that are chemically combined in a fixed ratio • Ex. H2O

  12. Physical and chemical properties differ between the elements that make up the compound and the compound itself • Ex. Oxygen and Hydrogen = gases Combined = liquid

  13. Atoms • Atom – smallest possible particle of an element • Greek atoms = invisible • Nucleus – consists of protons and neutrons and makes up most of the mass of the atom

  14. Proton – positively charged particle Neutron– neutral; particle with no charge • Electron – high energy, negatively charged particle with little mass

  15. Atoms • Orbital – 3D region around a nucleus that indicates the probable location of an electron • Each orbit holds a certain amount of electrons

  16. 1st orbit – 2 e • 2nd orbit – 8 e • 3rd orbit – 8 e

  17. Atoms • In order to be stable, an atom must have its outer orbit filled with electrons • Ex. He and Ne both have 8 e in their outer orbits

  18. Atoms have the same number of protons (+) as electrons (-), therefore, an atom is neutral

  19. Atoms • Periodic Table – chart that summarizes and organizes the elements • Chemical symbol – letters

  20. Atomic number – number of protons an atom has • Mass number – total number of protons + neutrons • Ex: F 9 protons 10 neutrons = 19 atomic mass

  21. Isotopes • Isotopes– atoms of the same element that have the same number of protons, but different number of neutrons

  22. Radioactive Isotope – one in which the nucleus decays over time, giving off radiation in the form of matter and energy • Used in research and in medicine

  23. Ionic Bonds • Ionic bond – the attractive force between oppositely charged ions which form when electrons are transferred from one atom to another

  24. Ion – electrically charged atom or molecule • Ex. NaCl

  25. Covalent Bonding • Covalent bond – forms when two atoms share one or more pairs of electrons • Ex. Water Oxygen 6 electrons needs two Hydrogen

  26. Molecules • Molecule – 2 or more atoms held together by a covalent bond • Ex. H20 or O2

  27. Models of Molecules • Chemical formula - #’s and types of atoms • Structural formula – how the atoms are linked by bonds • Space filling model– 3-D model with colored spheres

  28. Chemical Reactions • Chemical Reactions – breaking of old and formation of new chemical bonds resulting in a new substance • Reactants– starting materials for a rxn • Products – ending materials in a rxn

  29. Acids, Bases, and pH • H2O H+ + OH- • Hydroxide ion = OH- Hydronium ion = H+

  30. Acid – solution with more H+ • Ex. HCl • Base– solution with more OH- • Ex. NaOH

  31. pH Scale • pH scale – scale range from 0-14 that describes how acidic or basic a solution is • 0-6 acid 7 neutral 8-14 base

  32. Buffers • Buffer– substances that cause a solution to resist changes in pH Important because the slightest change in pH can be harmful to organisms • Ex. Blood

  33. On the back of your paper write: • Acids Neutral Base

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