Matter Chapter 2 1 Definition • Matter is anything that has mass and takes up space. • Mass is a measure of the amount of matter. • Volume is a measure of the amount of space. 2 Types of Matter • An element is a substance that cannot be separated or broken down into simpler substances by chemical means. • An atom is the smallest unit of an element that maintains the properties of that element. 3 Combinations of Matter • A compound is a substance made up of atoms of two or more different elements joined by chemical bonds. • A molecule is the smallest unit of a substance that keeps all of the physical and chemical properties of that substance. 4 Chemical Formulas • Chemical formula shows how many atoms of each element are in a unit of a substance. • Chemical symbols represent the element. • Subscripts indicate how many atoms of each element are in one molecule of the compound. 5 Mixtures • Pure substances is matter that has a fixed composition and definite properties. • A mixture is a combination of two or more substances that are not chemically combined. 6 Types of Mixtures • Heterogeneous mixture aren’t mixed uniformly and are not evenly distributed. • Homogeneous mixture are evenly distributed and the mixture is the same throughout. 7 What is used to define matter? 0 of 24 0% 0% nd Ne vo ith lu er m e. m as sn or vo lu m e. m as sa vo l um e 0% Bo th as s 0% m 1. mass 2. volume 3. Both mass and volume. 4. Neither mass nor volume. 10 What is the smallest part of an element? 0 of 24 0% 0% le cu ol e m m ixt ur e 0% po un d 0% co m atom compound mixture molecule at om 1. 2. 3. 4. 10 What do we call a physical combination of two or more substances? 0 of 24 0% le cu ol e m ixt m em el 0% ur e 0% en t 0% po un d compound element mixture molecule co m 1. 2. 3. 4. 10 What is milk an example of? 0 of 24 en t 0% el em en eo og Ho m He te r og en eo po un d 0% us m i. . . 0% us .. . 0% co m 1. compound 2. Heterogeneous mixture 3. Homogeneous mixture 4. element 10 Physical Properties • Physical Properties are characteristics of a substance that does not involve a chemical change, such as density, color or hardness. • Examples are melting point, boiling point, strength, hardness, conductivity, magnetism, heat. 12 Chemical Properties • Chemical properties are characteristics of matter that describes a substance's ability to participate in chemical reactions. • Examples are reactivity with oxygen, acid, water, or other substances; flammability. 13 Physical Changes • Physical changes are changes of matter from one form to another without a change in chemical properties. • Examples are cutting, dissolving, mixing, melting, evaporating, subliming. 14 Chemical Changes • Chemical changes are changes that occur when a substance changes composition by forming one or more new substances. • Examples are burning, rusting, and ripening of fruit. 15 Triple Point of Carbon Dioxide • Under certain conditions, you can see dry ice as a solid, liquid and gas all at the same time. • Dry ice under pressure will exhibit all three states of matter. • Under normal conditions, dry ice will sublime from a solid to a gas. 16 Kinetic Theory • All matter is made of atoms and molecules that act like tiny particles. • These tiny particles are always in motion. The higher the temperature of the substance, the faster the particles move. • At the same temperature, more massive particles move slower than less massive particles. 17 Different States of Matter • Solids – Definite volume. – Definite shape. – Low energy, molecules close together. • Liquids – Definite volume. – No definite shape. – More energy, molecules farther apart. 18 Different States of Matter • Gases – No definite volume. – No definite shape. – Lots of energy, molecules are very far apart. • Plasma – No definite shape. – Particles have been broken apart. 19 Energy in States of Matter • Energy is the ability to change or move matter. • Thermal energy is the total kinetic energy of the particles that make up an object. 20 Change in States of Matter • Evaporation is the change of a substance from a liquid to a gas. • Boiling point is the evaporation of a liquid at a certain temperature. • Sublimation is the process by which a solid turns directly into a gas. 21 Changes is States of Matter • Condensation is the changes of state from a gas to a liquid. • Melting is the process of a solid changing into a liquid. • Freezing is the reverse of melting. 22 Conservation of Mass & Energy • The law of conservation of mass states that mass cannot be created or destroyed. • The law of conservation of energy states that energy cannot be created or destroyed. 23 Fluids • Buoyant force is the upward force that fluids exert on matter. • All fluids exert pressure, which is the amount of force exerted on a given area. 24 Archimedes’ Principle • Archimedes Principle states that the buoyant force on an object in a fluid is an upward force equal to the weight of the fluid that the object displaces. 25 Fluid & Pressure • Pressure is the amount of force applied over an area. • Pressure=force/area 26 Pascal’s Principle • Pascal’s principle states that a change in pressure at any point in an enclosed fluid will be transmitted equally to all part of the fluid. 27 Fluids in motion • Viscosity is a liquid’s resistance to flow. • Bernoulli’s principle states that as the speed of a moving fluid increases, the pressure of the moving fluid decreases. 28 Properties of Gases • Gases have no definite shape or volume, and they expand to completely fill their container. • Gas particles move rapidly in all directions. • Gases are fluids. 29 Properties of Gases • Gases have no definite shape or volume, and they expand to completely fill their container. • Gas particles move rapidly in all directions. • Gases are fluids. 30 Properties of Gases • Gas molecules are in constant motion, and they frequently collide with one another and with the walls of their container. • Gases have a very low density because their particles are so far apart. Because of this property, gases are used to inflate tires and balloons. 31 Properties of Gases • Gases are compressible. • Gases spread out easily and mix with one another. Unlike solids and liquids, gases are mostly empty space. 32 Gas Laws • Gas laws explain the relationship between volume, temperature and pressure of gases. • Different Laws: – Boyle’s Law – Charles’ Law – Gay-Lussac’s Law 33 Boyle’s Law • Boyle’s Law states that for a fixed amount of gas at a constant temperature, the volume of a gas increases as its pressure decreases. • P1V1=P2V2 34 Charles’ Law • Charles Law states that for a fixed amount of gas at a constant pressure, the volume of the gas increases as its temperature increases. • K=V/T 35 Gay-Lussac’s Law • Gay-Lussac’s Law states that the pressure of a gas increases as the temperature increases if the volume of the gas does not change. 36 Atoms and the Periodic Table Chapter 4 37 Atomic Structure • Atoms are the simplest unit of a substance that still maintain the properties of the substance. • John Dalton proposed that atoms could not be divided. • Dalton also stated that atoms of different elements could join to form compounds. 38 Parts of an Atom • Atoms are composed of subatomic particles. • Protons and neutrons are found in the nucleus of the atom. • Electrons are found in orbitals around the nucleus of the atom. 39 Protons • Protons have a positive charge. • Protons have the mass of one amu (atomic mass unit). • The number of protons in an atom is characteristic of that element. • Each element has different number of protons. 40 Neutrons • Neutrons have no charge. • Neutrons have the mass of one amu. • Neutrons add to the mass of an atom. • Atoms of the same element with different number of neutrons have different masses (isotopes). 41 Electrons • Electrons have a negative charge. • Electrons have the mass of 1/2000 the mass of a proton. • The mass of an electron is insignificant. • The outer most electrons determine how elements combined in chemical compounds. 42 Quarks • A quark (IPA: /kwɔrk/) is a generic type of physical particle that forms one of the two basic constituents of matter, the other being the lepton. • Various species of quarks combine in specific ways to form protons and neutrons, in each case taking exactly three quarks to make the composite particle in question. 43 Models of Atoms • Niels Bohr suggested that electrons in an atom move in set paths around the nucleus. • Electrons can only be in certain energy levels. • Number of electrons=2n2 44 Electron Cloud Model • This model suggest that electrons orbit the nucleus in a cloud. • The regions in an atom where electrons are likely to be found are called orbitals. • The four different kinds of orbitals are the s, p, d and f orbitals. 45 Valence Electrons • An electron in the outermost energy level of an atom is called a valence electron. • Valence electrons determine an atom’s chemical properties and its ability to form bonds. 46 Periodic Table • The Periodic Law states that when elements are arranged this way, similarities in their properties will occur in a regular pattern. 47 Structure of the Periodic Table • Horizontal rows in the periodic table are called periods. • Atoms of elements in the same group, or column, have the same number of valence electrons, so these elements have similar properties. 48 Ions Formation • Atoms that gain or lose electrons form ions. • Elements that lose electrons have a positive charge (cation). • Elements that gain electrons have a negative charge (anion). 49 Periodic Information • The atomic number is the number of protons in an element. • The mass number of an atom equals the number of protons plus the number of neutrons. 50 Isotopes • Isotopes are atoms of the same element that have different number of neutrons. • Isotopes of the same element have different atomic masses. • The three isotopes of hydrogen are protium, deuterium & tritium. 51 Mass of Atoms • An atomic mass unit (amu) is equal to one-twelfth of the mass of a carbon 12 atom. • The average atomic mass for an element is a weighted average, so the more commonly found isotopes have a greater effect on the average than rare isotopes. 52 Squares on the Periodic Table • The chemical symbol is abbreviation of the chemical name. – The first letter of the chemical symbol is capitalized. – If there is more than one letter, the other letters are lower case. • Atomic number. • Average atomic mass. 53 Classifications of Elements • Metals are on the left side of the periodic table. • Nonmetals are on the right side of the periodic table. • Metalloids are located between the metals and nonmetals. 54 Alkali Metals • This is the most reactive group of metals. • Has only 1 valence electrons. • Reacts violently with water. • Elements include Li, Na, K, Rb, Cs & Fr. 55 Alkaline Earth Metals • Not as reactive as Alkali Metals. • Has two valence electrons. • Members include Be, Mg, Ca, Sr, Ba & Ra. 56 Transition Metals • Members have a wide variety of properties. • Has 1, 2 or 3 valence electrons. • Contain the coin metals: gold, silver & copper. • Contain the iron triad of Fe, Co & Ni. 57 Halogens • The most reactive group of nonmetals. • Has 7 valence electrons. • All members are poisonous. • Members include F, Cl, Br, I & At. 58 Noble Gases • Members contain a stable octet with 8 valence electrons. • These elements do not react with other elements. Don’t form compounds. • Members include He, Ne, Ar, Kr, Xe & Rn. 59 Semiconductors • Have the properties of both metals & nonmetals. • Used in the electronic industry. 60 Using Moles to Count Atoms • A mole is a collection of a very large number of particles. • Avagadro’s constant is the number of particles in a mole of a pure substance. • Avagadro’s constant is 6.022 x 1023/mol. 61 Molar Mass • Molar mass is the mass in grams of 1 mol of a substance. • The molar mass of an element in grams is the same as its average atomic mass in amu on the periodic table. 62 Converting Moles to Grams • Amount(mol) x molar mass of element/1 mol of element = mass(g) • Amount(mol)=1 mole of element/molar mass of element x mass(g) 63 Converting Amount to Mass • Determine the mass in grams of 5.50 mol of iron. • Given: amount of iron=5.50 mol mol Fe molar mass of iron=55.85 g/mol Fe • Unknown: mass of iron=?g Fe • 55.85 g Fe/1 mol Fe • 5.50 mol Fe x 55.85 g Fe/1 mol Fe=307 g Fe 64 Converting Amount to Mass • Determine the mass in grams of 5.50 mol of iron. • Given: amount of iron=5.50 mol mol Fe molar mass of iron=55.85 g/mol Fe • Unknown: mass of iron=?g Fe • 55.85 g Fe/1 mol Fe • 5.50 mol Fe x 55.85 g Fe/1 mol Fe=307 g Fe 65 The Structure of Matter Chapter 5 66 Compounds • Compounds are made from two or more elements. • The compound has properties that are different from those of the elements that make it. • Compounds always have the same chemical formula. 67 Chemical Bonds • The attractive forces that hold different atoms or ions together in compounds are called chemical bonds. • A bond length gives the distance between the nuclei of the two bonded atoms. • Bond angles tell how these atoms are oriented in space. 68 Structural Formulas • Structural formulas can show how the atoms are arranged in a compound. 69 What do we call the force that holds atoms in a molecule together? Atoms Chemical bond Nucleus Valence electrons 0% ro ns ec t uc le u on d el ce Va le n lb he C 0% s 0% m ic a A to m s 0% N 1. 2. 3. 4. 0 of 24 10 70 The properties of a compound are different than the properties of the elements that make up the compound. 1. True 2. False ls e 0% Fa 0 of 24 Tr ue 0% 10 71 Types of Bonds • Ionic bonds are formed between oppositely charged ions. • Metallic bonds are formed between atom’s nucleus and a neighboring atom’s electrons. • Covalent bonds are made between atoms of nonmetals. 72 Ionic Bond • Bond between a metal ion and a nonmetal ion. • The oppositely charged ions are attracted to each other. • Forms ionic solids. • High melting point. • Conduct electric current. 73 Metallic Bond • Bond that occur between atoms of metal. • Compounds are malleable and ductile. • Conduct electricity & heat. • Mixed to form alloys. 74 Covalent Bond • Bond formed between two nonmetals. • Share electrons. • Lower melting and boiling points than ionic compounds. • Covalent compounds are soft and squishy. • Covalent compounds tend to be more flammable than ionic compounds. 75 Polyatomic Ions • Polyatomic ions are groups of covalently bonded atoms that have either lost or gained electrons. • The group of atoms act as a single ion. • Polyatomic ions are put in parenthesis when you need to have more than one in a ion. HCO3− 76 Writing Chemical Formulas for Ionic Compounds • List the symbols for each ions. • Write the symbols for the ions with the cation first. • Find the least common multiple of the ions’ charges. • Write the chemical formula, indicating with subscripts how many of each ion are needed to make a neutral compound. 77 Naming Covalent Compounds • Name the element that is farthest to the left on the periodic table. • Add a prefix if there is more than one atom. • Name the element that is farthest to the right on the periodic table and change the ending to an –ide. 78 Writing Chemical Formulas for Covalent Compounds. • List the chemical symbols of the elements. • Add subscripts to indicate how many atoms of each element there is in a molecule of the compound. BaF2 79 Empirical vs. Molecular Formulas • Empirical formula shows the smallest whole-number ratio of atoms that are in a compound. • Molecular formula tells how many atoms are in one molecule of the compound. C6H12O6 80 Organic Compound • Organic compound is a covalently bonded compound made of molecules. • Organic compounds contain carbon and most of the time hydrogen. • Carbon can form four covalent bonds. • Compounds made of only hydrogen & carbon atoms are called hydrocarbons. 81 Types of Organic Compounds • Alkanes only have single covalent bonds. • Alkenes have double covalent bonds. • Alcohols have hydroxly or – OH group attached. 82 Alkanes • • • • • • • • • • Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane Decane 83 Alkenes • • • • • • • • • • Methene Ethene Propene Butene Pentene Hexene Heptene Octene Nonene Decene 84 Alcohols • • • • • • • • • • Methanol Ethanol Propanol Butanol Pentanol Hexanol Heptanol Octanol Nonanol Decanol 85 Polymers • Polymers are large molecule that is formed by more than five monomers or small units. • Polymers can be natural or synthetic. • Polymers elasticity varies depending on the structure. 86 Biochemical Compounds • Biochemical compounds are naturally occurring organic compounds that are very important to living things. • Type of biochemical compounds: – Carbohydrates (simple sugars) – Proteins (amino acids) – Lipids (fatty acids) 87 Chemical Reactions 8 West Science Investigations Types of Chemical Reactions • The left side of a chemical equations are the reactants. • The right side of a chemical equation are the products. • The arrow is the yield sign. CH4 + 2 O2 → CO2 + 2 H2O Energy in a Chemical Reactions • Chemical energy is the energy that comes from the bonds between two atoms. • Exothermic reaction releases energy during the reaction. • Endothermic reaction absorbs energy during the reaction. Reaction Types • Synthesis reaction involves combining substances to produce a new substance. • A + B → AB 2Na + Cl2 → 2 NaCl (formation of table salt) S + O2 → SO2 (formation of sulfur dioxide) 4 Fe + 3 O2 → 2 Fe2O3 (iron rusting) Reaction Types • Decomposition reactions involves substances that are broken apart. • AB → A + B 2H2O2 → 2H2O + O2 H2CO3 → H2O + CO2 CaCO3 → CaO + CO2 2KClO3 → 2KCl + 3O2 Reaction Types • Combustion reactions involves reactions that uses oxygen. • Oxygen is always in one of the reactants of the reaction. CH4 + 2O2 → CO2 + 2H2O + energy CH2S + 6F2 → CF4 + 2HF + SF6 Reaction Types • Single displacement reaction involves atoms of one element that 2AgNO3(aq) + Zn(s) → 2Ag(s) + Zn(NO3)2(aq) move into a compound, and atoms of the other Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g) element appear to move out. • A + BX → AX + B Reaction Types • Double displacement reaction involves two compounds that appear to exchange ions. • AX + BY → AY + BX HCl (aq) + NaOH (aq) → NaCl (aq) + H2O (l) AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3 (aq) Reaction Types • Oxidation-reduction reaction involves one atom losing electrons (oxidized) and another atom gains electrons (reduced). • Also called redox reaction. Balancing Chemical Equations 1. Identify the reactants and products. 2. Write a word equation for the reaction. 3. Write the equation using formulas for the elements and compounds in the word equation. 4. Balance the equation one element at a time by adding coefficients before each chemical formula. Rates of Change • Most reactions go faster at high temperatures. • A larger surface area speeds up reactions. • Concentrated solutions react faster. • Reactions are faster at higher pressure. • Massive , bulky molecules react slower. Catalyst & Inhibitors • Catalysts are added to reactions to make them go faster. • Inhibitors are catalysts that cause a reaction to go slower. Chemical Equilibrium • Most chemical reactions are not reversible. • Some changes are reversible. • Systems in equilibrium respond to minimize change. Le Chatelier’s Principle • If a change is made to a system in chemical equilibrium, the equilibrium shifts to oppose the change until a new equilibrium is reached. Homework • Chapter 6 Review, page 214-215, questions 128. Mixtures • Heterogeneous mixtures is composed of dissimilar components. • Homogeneous mixtures describes something that has a uniform structure or composition throughout. Types of Mixtures • Suspension is a mixture, that separates upon standing. • Colloid is a mixture where the particles are permanently suspended and never separate. • Emulsion is a colloid made of liquids that usually never mix. Solution • Solution is a mixture where something dissolve in something. • Solute is the part of a solution that is being dissolved. • Solvent is the part of a solution that is doing the dissolving. Factors that Affect the Rate of Dissolving. • Stirring • Surface area • Temperature Solubility • Concentration is the quantity of solute dissolved in the given volume of solvent. • Unsaturated solution contains less than the maximum amount of solute in the solvent • Saturated solution can not dissolve any more solute. • Supersaturated solution holds more solute than it normally can. Molarity • Concentrations can be expressed in molarity. • Molarity is expressed as moles per liter. • Molarity = moles of solute ÷ liters of solution. • M=mol ÷ L Acid & Bases Acids • Acid are substances that contain hydronium ions. • Properties: – High concentration of hydronium ions. – Sour taste – Turns blue litmus red – Reacts with metals Bases • Bases are substances that contain hydroxide ions. • Properties: – High concentrations of hydroxide ions. – Bitter taste. – Turn red litmus blue. – React with animal matter. pH • pH is the measure of the concentration of hydronium ions. • pH below seven is an acid. • pH above seven is a base. • pH of seven is neutral. Neutralization Reaction • Neutralization reaction occurs when an acid and a base are combined. • The reactants are acid and base. • The products are water and salt. • HCl+NaOH → H2O+NaCl Indicators • Indicators are chemicals that indicate the pH range of a solution • Examples: – – – – – Phenolphthalein Litmus pH paper Phenol red Methylene blue Acids vs. Bases • Acids dissolve in water ionize to form ions. • Bases dissolve in water dissociates to separate hydroxide ions. Task of the day. • Close your notes. • Write an essay comparing acid & bases based on what you know. • Minimum of 127.5 words!