Physical ScienceStudy Guide

Learning Target #1Explain what an element/compound is made ofa) Explain the differences in elements/compoundsb) Determine how many atoms are in a chemical formula

What is an atom?Atoms are the basic building blocks of ordinary matter. Atoms can join together to form molecules, which in turn form most of the objects around you

What is an element?A pure substance that cannot be separated into simpler substances by physical or chemical means.A pure substance in which there is only on type of particleA pure chemical substance consisting of only one type of atom

What is an example of an element?Every particle (atom) in a 5 g nugget of the element gold is like every other particle (atom) of gold

What is a unique characteristic of all elements?The particles (atoms) of a pure substance are alike no matter where that substance is found.

What factors help scientists tell the difference between different types of elements?Each element has a UNIQUE set of properties that allows you to identify it.Each element has its own characteristicsFactors may include:Physical properties (boiling point, melting point, and density)Chemical properties (reactivity with acid)

What elements are known as unreactive gases?HeliumKrypton

Why does a helium-filled balloon float up into the air if it is released?The density of helium is less than the density of air

Why does a krypton-filled balloon sink to the ground if it is released?The density of krypton is more than the density of air

How can elements be identified by their physical/chemical properties?Melting pointDensityColor

HardnessTextureFlammable

Reaction with oxygenReaction with acid

What 3 categories are elements divided into?MetalsNonmetalsMetalloids

What are unique characteristics about metals?ShinyGood conductors of electrical currentsMalleable (can be hammered into thin sheets)Ductile (they can be drawn into thin wires)

What are examples of metals?CopperCobalt

IronNickel

LeadTin

What are unique characteristics about nonmetals?Not shiny (dull)Poor conductors of electrical currentsSolids are brittle and nonmalleable

What are some examples of nonmetals?Neon – used in lightsGraphite (carbon) used in pencilsSulfurBromine

What are unique characteristics about metalloids?Semiconductors (properties of both metal and nonmetal)Some are shiny, some are dullSomewhat malleable and ducticleSome are conductors of electrical currents

What is an example of a metalloid?Silicon (used to make computer chips)AntimonyBoron What is a compound?A pure substance composed of two or more elements that are chemically combined.A particle is formed when atoms of two or more elements join together.A type of matter that forms when two or more elements combine chemicallyIn order for elements to combine, they must REACT (undergo a chemical change)It is a new pure substance that is different from the elements that reacted to form itCompounds are not random combinations of elements – when a compound forms, the elements join in a specific ratio according to their masses.

What is an example of a ratio of mass in terms of the compound water (hydrogen and oxygen)?1 g of mass of hydrogen TO 8 g of mass of oxygenEvery sample of water has a 1:8 ratio of hydrogen and oxygen

What are some basic compounds?H2O = water (hydrogen and oxygen)H2O2 = hydrogen peroxide (hydrogen and oxygen)NaCI = table salt (sodium and chlorine)*sodium is a soft, silvery white metal that reacts violently with water**chlorine by itself is a poisonous, greenish, yellow gas*Baking Soda = sodium, hydrogen, carbon, and oxygenSugar = carbon, hydrogen, and oxygenCarbon Dioxide = carbon and oxygen

What factors help scientists tell the difference between different types of compounds?Each compound has its own physical properties (boiling point, melting point, density, and color)Each compound has its own chemical properties (reaction with acid, reaction with light) etc….

How do I determine how many atoms are in a formula?

Chemical Formula Identify Elements Number of Atoms

CH4 Carbon carbon = 1Hydrogen hydrogen = 4

C6H12O6 Carbon carbon = 6Hydrogen hydrogen = 12Oxygen oxygen = 6

NaCI Sodium sodium = 1Chlorine chlorine = 1

Chemical formulas contain subscripts. What is the purpose of the subscript?It indicates the number of atoms of each element in a chemical formula

How many total atoms are in one molecule of sodium nitrate, NaNO3?Na = 1 N = 1 O = 3 Total = 5

Learning Target #2Explain the properties of matter: Physical Property – Chemical Propertya) Classify substances into groups according to their chemical/reactive properties

What is matter?Anything that has mass and takes up space

What are 2 methods used to describe matter?Physical propertiesChemical properties

What two ways can substances change?Physical changeChemical change

What is a physical change?The substance changes its appearance but not its molecular identity or structure.A substance changes its appearance but not its identity

What is a physical property?A characteristic of a substance that can be observed without changing the substance into another substance.

What are some examples of the differences between a physical change and a physical property? Start with an ice cube.

The ice cube melts to water - a physical change. The ice cube is cold - physical property.

Start with a piece of paper. Rip it up. That's a physical change. Burn the paper - a chemical change.

Find a glass cup. Throw it at a wall and shatter it. That's a physical change. Say the cup weighs about 1 pound. That's a physical property.

What are examples of a physical property?ColorHardnessTexture

ShineFlexibility

The temperature at which a solid meltsThe ability of a substance to dissolve in water

The ability of a substance to conduct heat and electricity

What are examples of physical change? shredding (ripping )a piece of paper folding paper into an airplane drawing on a piece of paper drawing a metal such as copper into a

wire pounding a metal such as aluminum

into thin sheets

breaking a sheet of glass ice cube melts into liquid water filtering a solid from a liquid

a liquid expanding as it is heated liquid water evaporates into water

vaporHow can a change in state be considered a physical change?

a) When water is boiled and becomes steam, a change of state occurs as it goes from liquid to gas. However, the water is still water (the water particles are still water particles)

b) When solid gold is melted, it changes state as it becomes a liquid. However, the gold has not changed its identity, (it is still gold)

What are examples of physical properties of water? Boils at 100 degrees C Freezes at 0 degrees C

Clear, colorless liquid at room temperature

What is a physical property of aluminum foil?Shiny

What is a physical property of a marshmallow?You can flatten and pull on it but the composition will stay the same

What is a chemical change?A substance changes its identityChanges matter from one form to anotherNew molecules are always formed

When 2 substances react to form a new material with different properties

What is a molecule?the simplest unit of a chemical compound that can exist, consisting of two or more atoms held together by chemical bonds

What is an example of a chemical change? silver metal reacting with sulfur to form

sulfur oxide (silver tarnishing, the silver appears darker)

burning hydrogen gas in air heating a compound until it breaks

down or decomposes

the oxidation of metals in air the reaction of an acid and a base burning gasoline two solutions are added together and

the new solution becomes hot

What are some common signs that a chemical change has occurred? Change in temperature The substance has changed color

The production of a solid The production of a gas

What is a chemical property?A characteristic of a substance that describes its ability to change into other substances.

What is the relationship between chemical properties and chemical changes ?The chemical properties of a substance (chemical formula) are special characteristics that influence the chemical reactions of this substance.

What type of evidence can demonstrate chemical properties?Burning Tarnishing Rusting

How do you observe chemical properties of a substance?You must change it to another substance

How can you tell when a chemical reaction occurs?Formation of new substances Changes in energy

What are examples of substances that can change chemically? When magnesium burns, it combines with oxygen in the air, forming magnesium oxide – the

flame produced when magnesium burned provides evidence that energy was released When iron combines with oxygen it forms Iron oxide (Rust) – The rust produced provides

evidence that energy was released When sodium hydroxide combines with hydrochloric acid, we will produce water and sodium

chloride, or table salt.

What are examples of chemical properties of water? Made of hydrogen atoms and oxygen

atoms in a 2 to 1 ratio Does not burn Reacts with some metals

What is an example of a chemical property of natural gas?It can burn

What is a chemical change of a marshmallow?The sugars will burn or cook, producing a crust made of new substances

What evidence is there in a green leaf that chemical reactions in the leaf produce chlorophyll?The leaf turns a darker shade of green

What other evidence is shown of a chemical reaction with a green leaf?Formation of water (type of condensation) – production of gas (oxygen) bubbles on the leaf

What happens to the atoms after a reaction has taken place? The atoms of the reactants have not changed. The atoms have combined in new ways to form different products with different molecules.

If the atoms after a reaction have not changed but the molecular identity of a substance has changed. What can we infer?It shows that chemical changes cause changes in matter

Learning Target #3Explain how mixtures can be separated using physical propertiesa) identify and explain different types of mixtures

What is a mixture? It is made up of two or more substances – elements, compounds, or both, that are together in

the same place but are not chemically combined Each substance has the same chemical makeup it had before the mixture was formed. No chemical changes

What is an example of a mixture? Cheese and Tomato Sauce do not react with each other when used to make a pizza Granite is made up of a mixture of three minerals: quartz, pink feldspar, and black mica:

different ratios of different mixtures give granite its various colors Salt water is a mixture of salt and water Air is a mixture of nitrogen, oxygen, carbon dioxide, and water vapor

How can a mixture be separated? Distillation: Separate salt from salt water by heating the mixture: Separate crude oil into

gasoline and kerosene Magnet: Separate a mixture of the elements iron and aluminum: iron is attracted to the

magnet, but aluminum is not Centrifuge: machine that separates components of the blood according to density Pick the pieces out Separation may require more than one step

How does a mixture differ from compounds?Each substance in a mixture keeps its individual properties

What are different types of mixtures?Solution Suspension Colloid

What is the difference between mixtures and compounds?Mixture Compound

Components are Components are elements elements, compounds, or both Components keep their original Components lose their original properties properties Separated by physical means Separated by chemical means Formed using any ratio of components Formed using a set mass ratio of

componentsWhat is a solution?A solution is a mixture that appears to be a single substance, but is composed of particles of two or more substances that are distributed evenly amongst each other

Often described as homogeneous mixtures (because they have the same appearance and properties throughout the mixture

Example: salt water --- salt is the solute and water is the solvent

What are examples of solutions in different states? Gas in gas----- dry air Gas in liquid----- soft drinks, tap water, gasoline, and many cleaning supplies Liquid in liquid ---- antifreeze Solid in liquid-----salt water Solid in solid ---- brass, steel

What is an alloy?Solid solutions of metals or nonmetals dissolved in metals.

What does dissolving mean?The process in which particles of substances separate and spread evenly throughout a mixture is known as dissolving.

What is a solute?The substance that is dissolved

What is a solvent?The substance in which the solute is dissolved

When two liquids or two gases form a solution, the substance with the greater volume is the solvent.

Why do the particles in a solution never settle out?The particles in solutions are so smallThey cannot be removed by filteringThey don’t even scatter light ( you can’t see the path of light through it )

What is concentration?A measure of the amount of solute dissolved in a solvent

Can be expressed in grams of solute per milliliter of solvent

How can a solution be described?ConcentratedDilute

What does solubility mean?The ability of a solute to dissolve in a solvent at a certain temperature

Can be expressed in grams of solute per 100mL of solvent

How do gases become less soluble (decrease) in liquids?The temperature is raised

What happens to the solubility of gases in liquids?It decreases as the temperature is raised

What happens when water is boiled?Bubbles of gas appear in hot water long before the water begins to boilThe gases that are dissolved in the water cannot remain dissolved as the temperature increases because the solubility of the gases is lower at higher temperatures

What happens to the solubility of most solids as the temperature gets higher?More solute can dissolve at higher temperatures.

What are three ways to make a solute dissolve faster? Mixing the solution (stirring or shaking) Heating the solution causes particles to move more quickly

Crushing the solute into smaller particles increases the amount of contact between solute and the solvent

What is a suspension?A suspension is a mixture in which particles of a material are dispersed throughout a liquid or a gas but are large enough that they settle out.

The particles in a suspension are large enough to scatter or block light A suspension can be separated by passing it through a filter (the liquid or gases pass through

easily, but the solid particles stay behind) Known as heterogeneous mixtures because the different components are easily seen Examples:

Shaking a snow globe to watch it snow, but then the snow settles on the bottomBlood (red blood cells, white blood cells, and platelets are suspended in a solution called plasmaMuddy waterItalian salad dressingMedicine

What is a colloid?A colloid is a mixture in which the particles are dispersed throughout but are not heavy enough to settle out.

Particles in a colloid are large enough to scatter light. A colloid cannot be separated by passing it through a filter.

Learning Target #4Explain/utilize the principle of conservation of mattera) Balance chemical reactions/simple version--total mass of reactant = total mass of product

What is matter? The stuff that makes up everything in

the world All objects are composed of matter.

What are examples of matter?Things you can easily see PlantsAnimals

RocksSoil

Water

Things you can't see Oxygen Air

What is law of conservation of matter? The total amount of matter of the reactants (mass of the reactants) must equal the total

amount of matter of the products (mass of the products) in a chemical reaction. Atoms cannot be created or lost in a chemical reaction. Atoms cannot be created or lost in a closed system, but can change form When substances undergo physical or chemical changes, matter is not created nor destroyed The number of atoms is not changed by a chemical reaction

What is unique about matter?Matter cannot be created or lost, but it can change forms.

Give an example of matter that has undergone a chemical changeFor example,If you burned charcoal, the charcoal would undergo a combustion reaction. If you added the masses of all the products of the reaction (ashes, soot, gases), however, you would find that this mass would be equal to the original mass of the charcoal. Mass was not created or lost, it just changed forms (from charcoal to ashes, soot, and gases).

How is matter affected in a chemical reaction? During a chemical reaction, matter is not created or destroyed This means that even though an object may have undergone a physical or chemical change, the

amount of matter (i.e. the mass) must always remain the same.

How are atoms affected in a chemical reaction?All atoms present at the start of the reaction are present at the end

What is a basic example of conservation of matter (mass)?A class is made up of a group of students and a teacher together in a roomWhen the bell rings, people from the class move from room to room, ending up in different classesThe number of people in the school has not changed ---- only the arrangement has. To describe a reaction accurately based on the law of conservation of matter, what must happen?A chemical equation must show the same number of each type of atom on both sides of the equationReactant + Reactant Product

In a chemical reaction, the total mass of the reactants is 10.0 grams. What is the total mass of the product?Exactly 10.0 grams

In a chemical reaction, the total mass of the reactants is 15.0 milliliters. What is the total mass of the product?Exactly 15.0 milliliters

What does the phrase “matter is conserved” mean?The amount of matter will stay the same

How much matter is in the following equations?1st exampleMagnesium metal (Mg) reacts with oxygen gas (O2) forming Magnesium oxide (MgO)Magnesium + Oxygen Magnesium Oxide

Reactants Product

.5g .2g .7g

2nd exampleHydrogen (H2)reacts with oxygen (O2) to form a product of water (H2O)Hydrogen + Oxygen Water Reactants Product 1.2g .6g 1.8