Matter and Change Chapter 1

Objectives Define Chemistry Define properties of matter

Objectives Identify and explain physical properties Density melting point boiling point Conductivity Malleability Identify and explain chemical properties the ability to form new substances. Distinguish between chemical and physical changes.

Objectives –Explain the difference between pure substances (elements and compounds) and mixtures. –Differentiate between heterogeneous and homogeneous mixtures. –Describe the three normal states of matter (solid, liquid, gas) in terms of energy, particle motion, and phase transitions.

Introduction to Chemistry Chemistry – the study of matter and the changes it undergoes the “central science”

Matter Anything that takes up space and has mass

The States of Matter SOLID LIQUID GAS PLASMA

States of Matter State of MatterVolumeShape SolidDefinite LiquidDefiniteIndefinite GasIndefinite PlasmaIndefiniteindefinite

Changes in State Name of Transitions between states of matter: –Melt/freeze –Boil/Condense –Sublimation/deposition Mostly obtained by heating or cooling (add or remove energy)

Solid Liquid Gas Melt Boil Condense Freeze

Classification of Matter

Matter Matter is classified into different categories based on the composition of the material Mixtures: matter consisting of a variable composition Pure substances: matter made of definite composition

Mixtures Are heterogeneous or homogeneous Are a physical blend of two or more pure substance Have variable composition Can be separated by physical change Separation Techniques depend on type of mixture

Heterogeneous Mixtures Uneven blend of two or more pure substances Different substances or phases of matter can be visibly seen Can be separated by physical means like filtration

Homogeneous Mixtures Also known as solutions Even blend of two or more pure substances Look uniform throughout the mixture Can be separated by physical means like distillation, crystallization or chromatography

Separation Techniques Heterogeneous Filtration Homogeneous Distillation Crystallization Chromatography

Study Buddy Review What is a mixture? What is the difference between a homogeneous and heterogeneous mixture? Provide an example of homogeneous and heterogeneous mixture.

Pure Substances Matter made of material with a unique set of chemical and physical properties Have constant composition Cannot be separated by physical change Are elements or compounds

Elements Pure substances that cannot be separated into simpler substances by a chemical change

Compounds Substance that contains two or more elements chemically combined in fixed (constant) proportions Can be separated into elements by chemical change Types: covalent or ionic

Study Buddy Review What is a pure substance? What is the difference between an element and a pure substance? Provide an example of an element and a compound. Where would you find a list of elements?

Which is it? Element Compound Mixture

Study Buddy Review What is a mixture? What is the difference between a homogeneous and heterogeneous mixture? Provide an example of homogeneous and heterogeneous mixture.

Physical and Chemical Properties

Properties of Matter Physical Properties Property of an object that can be observed or measured without changing the substance Examples and values for water: –Density1 g / 1 mL or 1 g / cm 3 –Colorcolorless –Freezing Point0 o C

Density Density is the mass per unit volume of a substance D = mass / volume –Measured in g / mL or g / cm 3 Less dense objects float on more dense objects Density of liquid water is more than density of ice (so ice floats in liquid water)

Significance of Physical Properties Help to identify a substance Examples: –Density –Melting Point –Boiling Point

Properties of Matter Chemical Properties Relates to a substance’s ability to undergo changes that transform it into different substances Examples : –flammability –Ability to rust

How do you know if chemical reaction occurred? Chemical changes produce new, different substances –Precipitate formed (solid) –Gas formed (bubbling) –Energy change occurs (colder or hotter) –Color change (can also be physical—be careful!)

Significance of Chemical Properties Chemical changes are chemical reactions Examples: –Combustion –Oxidation –neutralization

Extensive and Intensive Properties Extensive: depend on the amount of matter that is present Examples: –Mass –Volume –energy Intensive: do NOT depend on the amount of matter that is present Examples: –Melting point –Density –temperature

Law of Conservation of Energy Law of Conservation of Energy: in all physical and chemical changes, energy is neither created or destroyed Energy: the capacity to do work or produce heat Measured in Joules (SI unit)

Law of Conservation of Matter Law of Conservation of Matter: in all chemical and physical changes, matter is neither created or destroyed A chemical change is a really chemical reaction 4 Fe + 3 O 2  2 Fe 2 O 3 Reactants  products Antoine Lavoisier: –Made accurate and precise measurements during chemical reactions

Study Buddy Review Classify each as a physical or chemical property of matter: Blue Color Ability to Rust Density Flammability Reacts with a base to form water Boiling Point Reacts with water to form a gas Luster Mass Odor