Physical States of Matter Solid: Definite shape and definite volume Particles tightly packed, held in rigid positions Can not be compressed Liquid: Variable shape and definite volume, Particles loosely packed, move freely, compress slightly Gas: Variable shape and Variable volume. Particles move freely and Can be easily compressed *Iron becomes liquid at o C and gas >3000 o C *Water exists in all three forms under natural conditions

States of Water

Physical changes Gas Deposition Condensation Evaporation Melting Solid Liquid Freezing Sublimation

Elements, Compounds, and Mixtures Heterogeneous Mixture: It can be separated into pure substances by physical methods. The properties are not constant Ex: Quartz rock is a heterogeneous mixture of gold and sand. They can be separated by difference in their density. Homogeneous mixture can also be separated by physical methods. The properties of given sample are constant. However, the properties may vary from sample to sample.

Mixtures Alloy: It is a homogeneous mixture of two or more metals Ex: Gold is gold, silver and copper. The percentage gold varies in 10K, 14K and 18K (42- 75% Substance: It is a matter that has definite composition and constant properties. A substance can be an element or a compound

Elements and Compounds Element: It is substance that can not be separated or broken down further by chemical or physical methods. Compound: It contains two or more elements that can be broken into pure elements by chemical method. Ex: Sugar can broken down into Carbon, Hydrogen and Oxygen by chemical method

Elements and Compounds

Elements, Compounds and Mixtures

Genesis of Names and Symbols of Elements 1) Over 100 elements are present 2) Only 10 elements account of 95% of the mass of earth 3) Earth: 49.5% Oxygen, 25.7% Silicon, 7.5% Aluminum, 4.7% Iron, 3.4% calcium, 9.2% other elements

Names and Symbols of Elements Hydrogen: A Greek word meaning water former Carbon: Latin word Carbo, meaning coal Calcium: Derived from Latin word calcis, (lime) Germanium: Germany Scandium: Scandinavia Curium: Marie Curie (scientist) Nobelium: Alfred Nobel

Names and Symbols of Elements John Dalton’s Proposal: Elements are composed of indivisible, spherical particles, called as atoms (Greek word atomos meaning indivisible)

Names and Symbols of Elements IN 1813, J.J. Berzelius proposed the current system Berzelius Proposal: 1) A symbol corresponds to the first letter of the name of the element Ex: H, C, O 2) When the elements start with the same letter, two letters from the name should be used as symbol. Ex: Ca, Cd, Cl

Symbols from Latin names Pb: for Lead, Latin name is plumbum Hg: Mercury, Latin name Hydrargyro (liquid silver) Au (Gold), Na (Sodiuim), K (Potassium), Sb (Antimony), Sn (Tin), Cu (Copper), Fe (Iron)

Conventional writing of symbols The first letter should always be capitalized and the second should in lowercase. Ex: Co (Cobalt

Periodic Table of the Elements All the elements have been arranged by atomic number a) B, Si, Ge, As, Sb,Te,Po, At are semimetals b) H, C, N, O, F, Ne, P, S, Cl, Ar, Se, Br, Kr, I, Xe, Rn are nonmetals c) Hg, Br are liquids

Metals, Nonmetals and Semimetals A metal is an element, typically a solid, has a bright metallic luster, high density, high melting point and is a good conductor of heat and electricity. A metal can be hammered into a thin sheet of foil (malleability) If a metal can be drawn into a fine wire, it is said to be ductile. Ex: Aluminum, copper and silver

Nonmetals Low density Low melting point Poor conductors Occur in mostly solid and gaseous state Solids are neither malleable nor ductile

General characteristics of Metals and Nonmetals PROPERTYMetalsNonmetals Physical stateSolidSolid, gas AppearanceMetallic lusterDull PliabilityMalleable, ductilebrittle ConductivityHeat and electricityNonconductor DensityUsually highUsually low Melting pointUsually highUsually low Chemical reactivityReact with nonmetals React with metals and nonmetals

Semimetals Semimetals are called metalloids. Properties are midway between metals and nonmetals. Ex: Silicon is a semiconductor, used in transistors and integrated circuits.

Physical state of Elements All the metals, except Mercury, are solids. All the semimetals are also in solid state Nonmetals show great diversity. At 25 o C, and normal pressure, five nonmetals are solids, one is liquid and eleven are gases.

Compounds and Chemical formulas Compounds always contain the same elements in a constant proportion by mass - French chemist Joseph Louis Proust Example: NaCl contains 39.3% Sodium and 60.7% Chlorine Water contains 11.25% Hydrogen, 88.8% Oxygen

Compounds and Chemical formulas The number of atoms is indicated with subscript, unless the number is 1 Ex: H 2 O, NH 3, O 2, H 2, Cl 2

Chemical formulas Some chemical formulas use parentheses to clarify chemical composition C 2 H 4 (OH) 2

Vitamin B Vitamin B 3 : C 6 H 6 N 2 O Vitamin B 6 : 8 Carbon atoms 11 Hydrogen atoms 1 Nitrogen atom 3 Oxygen atoms Write the formula

Properties of Matter *Properties are the distinguishing characteristics of a substance that are used in its identification and description * Each chemical substance has a unique set of properties that distinguishes it from other substances

Physical and Chemical properties Physical property: Characteristic of a substance that can be observed without changing the substance into another substance Ex: Color, odor, taste, size, physical state, density, melting point and boiling point Chemical property: Characteristic of a substance that describes the way it undergoes or resists change to form anew substance Ex: Rusting nails is chemical property of iron

Chemical properties * Changes associate with chemical properties result from the interaction of a substance with one or more other substances *Sometimes the presence of energy (heat, light) and pressure also triggers the change. (ex: decomposition of Hydrogen peroxide into water and oxygen)

Physical and chemical properties of Water PhysicalChemical 1)Colorless 2)Odorless 3)Boiling point = 100 o C 4)Freezing point = 0 0 C 5)Density = 1.000g/ml at 4 o C 1)Reacts with bromine to form a mixture of two acids 2)Can be decomposed by means of electricity to form hydrogen and oxygen 3)Reacts vigorously with sodium metal to produce hydrogen 4)Does not react with gold even at high temperatures 5)Reacts with carbon monoxide at elevated temperature to produce carbon dioxide

Intensive and Extensive properties Intensive property: A property that is independent of the amount of substance Ex: Temperature (boiling and melting points), color, density and all chemical properties Extensive property: A property that depends on the amount of substance Mass, Volume, length

Changes in Matter Physical change: It is a process in which a substance changes its physical appearance but not chemical composition. Ex: NaCl in water Chemical Change: It is process in which a substance undergoes a change in chemical composition Irreversible and original substance can not be recovered

Gray areas 1) Hydrochloric acid in water cannot be recovered 2) Cooking of an egg

Change Classification Rusting of iron Chemical Melting of snow Physical Digesting food Chemical taking a bite of food Physical Burning gasoline Chemical Slicing an anion Physical Detonation of dynamite Chemical Souring milk Chemical Breaking of glass Physical

Conservation of Mass Law of conservation of mass (By Antoine Lavoisier, 1789) “Matter can be neither created not destroyed” If 1g Hydrogen combines with 8g of Oxygen, the resulting water will be 9g If 9g water decomposes, it will produce 1g Hydrogen and 8g oxygen g of Magnesium was burned with oxygen to give 4.030g of Magnesium oxide powder. What is the mass of Oxygen?

Potential Energy and Kinetic Energy Potential Energy: The energy that mater possesses as a result of its position or composition Kinetic Energy: The energy matter has as a result of its motion.

Properties and physical states As the temperature increases, the kinetic energy of matter increases. Property of particleSolidLiquidGas Kinetic Energy Movement Very low Negligible High Restricted Very high Unrestricted

Conservation of Energy Law of conservation of energy: Energy can not be created nor destroyed. Energy can be converted from one form to another 1g of water requires 540 cal to become steam. When steam cools down to become water, it releases 540 cal energy Heat of energy absorbed 1g water cal 100 C 1g steam Heat of energy released

Energy and chemical changes Energy absorbed Water + electrical energy Hydrogen + Oxygen Energy released Hydrogen + Oxygen Water + Heat energy

Forms of Energy Heat Light Chemical Electrical Mechanical Nuclear All forms of energy are convertible Ex: Solar panels (Light to electrical) Turbine spins and drives an electrical generator (Mechanical to electrical)

Conservation of mass and energy E = mc 2 Energy E and mass (m) are related by the velocity of light (c) Total mass and energy in the universe is constant Application in chemistry In a chemical reaction, the law indicates that the total mass and energy before and after a chemical change is constant.