Chemistry Diamond Water Sugar Diamond (carbon) = C Water = H2O Sugar = C6H12O6 The combination of carbon and water contains the same elements as sugar. . Elements: can’t be broken into simpler substances (atoms.) Sugar + water…would you drink this? Ash + water…would you drink this? Why? They contain the same elements don’t they? Why don’t you get sugar when you mix water with the coal? The elements (carbon in coal; hydrogen and oxygen in water) only combine as sugar when chemical bonds form Sugar cannot be easily separated into its components. So…Can you break gold down into a simpler substance??? NO…because it is an element! Atoms are the basic building blocks of all matter. The structure of an atom The center of an atom is called the nucleus All nuclei contain positively charged particles called protons (p+). Most contain particles that have no charge, called neutrons (n0). Example: Carbon has 6 protons so its atomic number is 6 The space surrounding the nucleus contains extremely small, negatively charged particles called electrons (e-) This region of space is an electron cloud. Because opposites attract, the electrons are held in the electron cloud by the + nucleus. Nucleus Electron energy levels Atoms contain equal numbers of electrons and protons; therefore, they have no net charge. Particle Location Charge Symbol Electron Surrounding nucleus - e- Neutron Nuclei None no Proton Nuclei + p+ Compounds and Bonding • A compound is a substance that is composed of atoms of two or more different elements that are chemically combined. • Table salt (NaCl) is a compound composed of the elements sodium and chlorine. How covalent bonds form • A covalent bond holds the two hydrogen atoms together. • A molecule is a group of atoms held together by covalent bonds. It has no overall charge. Water molecule st 1 2 electrons in the electron shell 8 electrons in the 2nd electron shell 18 electrons in the 3rd electron shell •Not notes! Just cool •This is an actual picture (the 1st EVER) of a molecule. This is a picture of the smallest thing ever taken! Pentacene is a polycyclic aromatic hydrocarbon consisting of five linearly-fused benzene rings. Used in dyes and solar cells. How ionic bonds form • An atom (or group of atoms) that gains or loses electrons has an electrical charge and is called an ion. An ion is a charged particle made of atoms. • The attractive force between two ions of opposite charge is known as an ionic bond. Writing chemical equations • In a chemical reaction, substances that undergo chemical reactions, are called reactants. • Substances formed by chemical reactions, are called products. •CO2 + H2O-----yields----H2CO3 (carbonic acid) is a sample chemical reaction in living things •Reactants are on the left side of the equation, while products are on the right side Writing chemical equations • A molecule of table sugar can be represented by the formula: C12H22O11. •Atoms are neither created nor destroyed in chemical reactions. They are simply rearranged. •A mixture is a combination of substances in which the individual components retain their own properties. Ex: sand + sugar • Neither component of the mixture changes. Heterogeneous Mixtures A mixture that is NOT mixed evenly throughout & each component keeps its own properties. •Rocks •Salad •Chicken Noodle •Soup Mixtures and Solutions • A solution is a mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent). •Ex. Sugar + Water + Kool Aid •Can’t separate Phases of Matter Solid Matter with definite shape & volume. Tightly packed particles that mainly vibrate. Liquid • Matter with a definite volume but no definite shape. • Particles flow freely from one place to another. Gas Matter that doesn’t have definite volume or shape. Particles move at high speeds in all directions Heating Curve of Water •100oC •solid •liquid •gas •0oC •-20oC •Time (Increasing) •Heat Energy (Increasing) Plasma • State of electrically charged free moving particles. Physical Changes The form or appearance of matter changes, but not its composition. Dissolving Changing State/Phase Absorption Cutting/Tearing/Smashing Chemical Changes Changing from one substance into a new substance. Color change Forming a gas or solid Producing light Odors Giving off heat Absorbing heat The Periodic Table Classification of the Elements Metals Most of the elements are solid metals. Metals are usually shiny, malleable, good conductors of heat & electricity and ductile. Metalloids Elements that have some characteristics of both metals & nonmetals. - Examples: Boron, Silicon, Antimony, & Arsenic Nonmetals Most •Liquid O2 •Sulfur nonmetals are gases. Solid nonmetals are brittle, poor conductors, & not easily shaped. 97% of your body is made of nonmetals Elements Atomic Number Shows the number of protons in the nucleus. Every atom of that element has only that number of protons. Mass Number Number of protons plus neutrons. Isotopes: Atoms of the same element with different numbers of neutrons. Examples: Hydrogen-1, Hydrogen-2, Hydrogen-3 Carbon-12, Carbon-14 Used to treat cancer & radioactive dating Atomic Mass The weighted average of the isotopes of an element. Measured in mass units (u) •Atomic Number •47 •Ag •Silver •107.868 •Atomic Mass •Chemical •Symbol The Periodic Table * Arranged according to atomic number and similar properties. Periods A row (horizontal) of elements. The properties gradually change predictably across the period. Groups/Families Usually the vertical columns of elements that have similar physical & chemical properties. 3 4 Li Be 11 12 Na Mg 19 20 K Ca 37 38 Rb Sr 55 56 Cs Ba 87 88 Fr Ra Alkali Metals Most reactive of the elements. Not naturally found by itself. Has a single electron in its outermost shell. Column #1 Alkaline Earth Metals Commonly used in fireworks for the colors. Has 2 electrons in the outermost shell. Column #2 Transition Elements • Wide variety of metals such as coin & structural metals. • Middle of the periodic table. • Examples: Gold, Silver, Mercury, Lead, & Copper 9 F 17 Cl Halogens 35 Br 53 I 85 At 117 Bond with Alkali Metals to form salts. Have 7 electrons in outermost shell. Steal electrons from other atoms. Column #17 2 Noble Gases He 10 Ne 18 Ar 36 Kr 54 Xe 86 Rn 118 Only naturally stable elements. Have a full outermost shell of electrons (8) Found in small amounts in the atmosphere. Heated to produce colorful light. Column #18 Carbon Compounds Foundation for life Carbohydrates, Lipids/Fats, Proteins, & Amino Acids. Hydrocarbons - long chains of Hydrogen & Carbon atoms :Alcohols & Fuels Law of Conservation of Mass The mass of the reactants will equal the mass of the products. Energy in Reactions 1. Endothermic – reaction where energy is absorbed. 2H2O + energy 2H2 + O2 2. Exothermic – reaction where energy is released. C6H12O6 + O2 H2O + CO2 + energy Rates of Reaction (things that affect the rate) 1. Temperature 2. Surface Area 3. Pressure 4. Catalyst – a substance that speeds up a chemical reaction. (Enzymes) Water • Water resists changes in temperature. • Water is one of the few substances that expands when it freezes. • Ice is less dense than liquid water so it floats as it forms in a body of water. Adhesion and Cohesion Water is attracted to other water. This is called cohesion. water on a penny! Water can also be attracted to other materials. This is called adhesion. Caused by adhesion the water runs along the glass and does not fall straight. Fin