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Delve into the essential components of life chemistry, from matter and elements to atoms and chemical reactions. Understand the role of energy and the states of matter. Watch videos to grasp key concepts.
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Chemistry of Life Honors Biology: Chapter 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?
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)
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
Elements and Atoms • Atom- simplest particle of an element that retains all of the properties of that element. Nucleus
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.
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
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
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).
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
Compounds • http://gtm-media.discoveryeducation.com/videos/Discovering the Elements/sec2941_300k.asf
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)
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
Chemical Bonds • Attractive forces holding atoms together. • Covalent Bond • Ionic Bond • Hydrogen bond
Covalent Bond • Formed when 2 atoms SHARE 1+ pairs of valence electrons.
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-)
??Element or Compound?? • HCl • CO2 • Cl • Li • H2O HCl, CO2, and H2O- compounds Cl and Li- elements
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
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
Solids • Move less rapidly than liquids or gases • Fixed volume • Molecules/atoms more closely linked than liquids or gases (with the exception of H2O).
Liquid • Maintain a fixed volume, but particles move more freely ability to flow and conform to container’s shape.
Gas • Particles move rapidly • Little to no attraction to each other. • Fill the volume of the container they occupy.
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?
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.
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.
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
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.
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-
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.