Unit 1 Matter: Properties and Change

Matter: Properties and Change Objectives Students should be able to: Students should be able to: Distinguish between chemical and physical properties Distinguish between chemical and physical properties Apply the Law of Conservation of Mass to chemical reactions Apply the Law of Conservation of Mass to chemical reactions Classify matter as elements, compounds, or mixtures Classify matter as elements, compounds, or mixtures Contrast homogenous and heterogeneous mixtures Contrast homogenous and heterogeneous mixtures Describe techniques used to separate mixtures Describe techniques used to separate mixtures

What is matter? Matter – anything that takes up space and has mass. Matter – anything that takes up space and has mass. Mass – a measure of the amount of matter in an object Mass – a measure of the amount of matter in an object Weight is due to gravity; it changes from location to location; mass is always constant. Weight is due to gravity; it changes from location to location; mass is always constant.

States of Matter Definite Shape Definite Volume Temperature increase Compressible SolidYesYes Small expansion No LiquidNoYes Small/moderate expansion No Gas/VaporNoNo Large expansion Yes

Vapor – gas form of a substance that is normally a liquid at room temperature. Vapor – gas form of a substance that is normally a liquid at room temperature.

Types of Matter I. Pure Substance- one particular kind of matter; is uniform (all the same) and has a definite composition A. Elements – simplest kind of matter cannot be broken down any simpler cannot be broken down any simpler composed of only one kind of atom. composed of only one kind of atom. written shorthand w/ chemical symbols written shorthand w/ chemical symbols ex: carbon = C, iron = Fe, mercury = Hg

B. Compounds – made of two or more elements, chemically combined broken down only by chemical change broken down only by chemical change when broken down, pieces have different properties than original compound. when broken down, pieces have different properties than original compound. adhere to Law of Definite Proportions – compound is always made of the same elements in the same proportions by mass adhere to Law of Definite Proportions – compound is always made of the same elements in the same proportions by mass ex: water = H 2 O, 2:1 ratio H to O methane = CH 4, 4:1 ratio H to C methane = CH 4, 4:1 ratio H to C

II. Mixture- more than one kind of matter physically combined –has a variable composition –each part keeps its own properties –can be separated by physical means

A. Heterogeneous- mixture is not uniform in composition, (visibly different parts) ex: chocolate chip cookie, soil B. Homogeneous- same composition throughout; (all looks the same); Aka - solutions ex: Gatorade, air, salt water

Separating Mixtures Distillation – separates components of solution w/ different boiling points Distillation – separates components of solution w/ different boiling points Filtration – separates solid from a liquid using porous barrier Filtration – separates solid from a liquid using porous barrier Crystallization – forms pure solid particles from a saturated solution of dissolved particles Crystallization – forms pure solid particles from a saturated solution of dissolved particles Chromatography – separates components (mobile phase) across a piece of paper (stationary phase) Chromatography – separates components (mobile phase) across a piece of paper (stationary phase)

Properties of Matter I. Physical Properties – can be observed and measured without changing the composition. color, odor, texture, hardness, density, melting and boiling pts. color, odor, texture, hardness, density, melting and boiling pts. Physical change – change in appearance without changing the composition. ex: boil, freeze, dissolve, melt, condense, cut, bend, split, crack ex: boil, freeze, dissolve, melt, condense, cut, bend, split, crack

II. Chemical Properties – can only be observed by changing the composition of the material. Chemical change – a change where a new kind of matter is formed. Chemical change – a change where a new kind of matter is formed. ex: rust, rot, explode, burn, decompose, ferment ex: rust, rot, explode, burn, decompose, ferment

Indications of a Chemical Change Energy absorbed or released – temperature gets hotter/colder Energy absorbed or released – temperature gets hotter/colder Color change (sometimes) Color change (sometimes) Gas production – bubbling, fizzing, or odor change Gas production – bubbling, fizzing, or odor change Precipitate formed – solid that separates from solution and won’t re-dissolve Precipitate formed – solid that separates from solution and won’t re-dissolve

Law of Conservation of Mass matter can not be created or destroyed in chemical reactions – it is conserved matter can not be created or destroyed in chemical reactions – it is conserved Example: 2Na + Cl 2 2 NaCl reactants products 200 g + 15 g = 215 g 200 g + 15 g = 215 g mass of reactants = mass of products

A. Extensive vs. Intensive Extensive Property Extensive Property –depends on the amount of matter present Intensive Property Intensive Property –depends on the identity of substance, not the amount

A. Extensive vs. Intensive Examples: Examples: –boiling point –volume –mass –density –conductivity intensiveextensiveextensiveintensiveintensive

B. Physical vs. Chemical Physical Property Physical Property –can be observed without changing the identity of the substance Chemical Property Chemical Property –describes the ability of a substance to undergo changes in identity

B. Physical vs. Chemical Examples: Examples: –melting point –flammable –density –magnetic –tarnishes in air physicalchemicalphysicalphysicalchemical

B. Physical vs. Chemical Physical Change Physical Change –changes the form of a substance without changing its identity –properties remain the same Chemical Change Chemical Change –changes the identity of a substance –products have different properties

B. Physical vs. Chemical Signs of a Chemical Change Signs of a Chemical Change –change in color or odor –formation of a gas –formation of a precipitate (solid) –change in light or heat

B. Physical vs. Chemical Examples: Examples: –rusting iron –dissolving in water –burning a log –melting ice –grinding spices chemicalphysicalchemicalphysicalphysical