Chapter 4Chapter 4P. 85 - 109P. 85 - 109

Mixtures, Mixtures, Elements Elements

and and CompoundsCompounds

Classes of Matter – How do Classes of Matter – How do humans organize all of the humans organize all of the

matter that matters? matter that matters? Classification system – a way of Classification system – a way of

organizing or grouping objects organizing or grouping objects according to their characteristics.according to their characteristics.

Classifying objects makes it easier to Classifying objects makes it easier to organize them.organize them.

Matter needs to be classified…so Matter needs to be classified…so why not use the phases of matter to why not use the phases of matter to organize matter?organize matter?

How do we Classify Matter?How do we Classify Matter? Scientists classify matter according to Scientists classify matter according to

its makeup – (how matter is its makeup – (how matter is “constructed”)“constructed”)

Matter can exist as:Matter can exist as: I. MixturesI. Mixtures II. SolutionsII. Solutions III. ElementsIII. Elements IV. CompoundsIV. Compounds

I. MixturesI. Mixtures Def.Def. - - Matter that consists of two Matter that consists of two

or more substances mixed or more substances mixed together but together but NOTNOT chemically chemically combined.combined.

Properties of Mixtures Properties of Mixtures Substances are not chemically combinedSubstances are not chemically combined Substances may change in physical Substances may change in physical

appearance – ex – dissolving sugar in appearance – ex – dissolving sugar in water – water and sugar still exist – they water – water and sugar still exist – they have not changed chemicallyhave not changed chemically

Substances that make up mixtures can be Substances that make up mixtures can be present in any amount. (any ratio)present in any amount. (any ratio)

Mixtures can be separated out by simple Mixtures can be separated out by simple physical meansphysical means

Separating a Mixture Separating a Mixture ActivityActivity

Given a mixture of iron filings, Given a mixture of iron filings, sand and salt, separate the three sand and salt, separate the three components of the mixture out components of the mixture out using the physical properties of using the physical properties of each component.each component.

Write the step-by-step procedure Write the step-by-step procedure for separating this mixture.for separating this mixture.

Two Types of MixturesTwo Types of Mixtures 1) 1) Heterogeneous – Def. a mixture Heterogeneous – Def. a mixture

that does not appear to be the same that does not appear to be the same throughout.throughout. Appears to be the “least mixed” of all the Appears to be the “least mixed” of all the

mixtures.mixtures. Particles in it are large enough to be seen Particles in it are large enough to be seen

and separated from each other.and separated from each other. Particles settle when allowed to stand.Particles settle when allowed to stand. Ex – pebbles in water (L&S), oil and vinegar Ex – pebbles in water (L&S), oil and vinegar

(L&L), chex mix (S&S), etc.(L&L), chex mix (S&S), etc.

Two Types of Two Types of MixturesMixtures 2) 2) Homogeneous – Def. a mixture Homogeneous – Def. a mixture

that appears to be the same that appears to be the same throughoutthroughout Is a “well mixed” mixture.Is a “well mixed” mixture. Particles in it are very small and not easily Particles in it are very small and not easily

recognizable.recognizable. Particles do not settle when allowed to Particles do not settle when allowed to

stand.stand. Ex – stainless steel, gold jewelry, chocolateEx – stainless steel, gold jewelry, chocolate

ColloidsColloids Special type of homogenous mixture is a Special type of homogenous mixture is a

colloid - milk, whipped cream, mayonnaise, colloid - milk, whipped cream, mayonnaise, toothpaste are all examplestoothpaste are all examples

Particles are relatively large in sizeParticles are relatively large in size Particles are kept permanently suspended – Particles are kept permanently suspended –

(they won’t settle out)(they won’t settle out) Colloids often appear cloudyColloids often appear cloudy

Jello (L in S)Jello (L in S) Whipped Cream (G in L)Whipped Cream (G in L) Smoke (S in G)Smoke (S in G) Fog (L in G)Fog (L in G) Mayonaise ( L in L)Mayonaise ( L in L) Paint (S in L)Paint (S in L) Butter (L in S)Butter (L in S)

SolutionsSolutions Solution – Def. – A type of Solution – Def. – A type of

homogeneous mixture of two or more homogeneous mixture of two or more substances in a single physical state.substances in a single physical state.

It is the “best mixed “ of all mixtures.It is the “best mixed “ of all mixtures. Examples:Examples:

Ocean water, iced tea, lemonade, Ocean water, iced tea, lemonade, antifreeze, lava!, air!antifreeze, lava!, air!

Properties of SolutionsProperties of Solutions Always has a substance being Always has a substance being

dissolved (solute) and a substance dissolved (solute) and a substance that does the dissolving (solvent).that does the dissolving (solvent).

Particles are so small, they can’t be Particles are so small, they can’t be separated by simple physical means.separated by simple physical means.

Particles are too small to scatter light Particles are too small to scatter light like colloids.like colloids.

Particles are evenly spread out.Particles are evenly spread out.

The “Sol…” WordsThe “Sol…” Words SolutionSolution – a type of homogeneous mixture of – a type of homogeneous mixture of

2 or more substances in a single physical 2 or more substances in a single physical state.state.

SolventSolvent – the substance that does the – the substance that does the dissolving – ex water.dissolving – ex water.

SoluteSolute – the substance that is dissolved – ex – the substance that is dissolved – ex salt, sugar, drink mix.salt, sugar, drink mix.

SolubleSoluble – a substance that that will dissolve in – a substance that that will dissolve in another substance is said to be “soluble”another substance is said to be “soluble”

SolubilitySolubility – the amount of solute that can be – the amount of solute that can be completely dissolved in a given amount of completely dissolved in a given amount of solvent at a specific temperature.solvent at a specific temperature.

Special Solutions…Special Solutions… Solutions may exist as gases (air), Solutions may exist as gases (air),

liquids (iced tea) or solids (alloy).liquids (iced tea) or solids (alloy). Alloy – def. a metal solution of a solid Alloy – def. a metal solution of a solid

dissolved in a solid.dissolved in a solid. ExamplesExamples

Gold jewelry = gold & copperGold jewelry = gold & copper Brass = copper & ZincBrass = copper & Zinc Sterling Silver = silver & copperSterling Silver = silver & copper Stainless steel = iron & chromiumStainless steel = iron & chromium

II. ElementsII. Elements Before you understand what an Before you understand what an

element is, you have to understand element is, you have to understand what a pure substance is…what a pure substance is…

Pure substance – def – made of only Pure substance – def – made of only one kind of material and has definite one kind of material and has definite properties. It’s the same throughout properties. It’s the same throughout and all of the particles in a pure and all of the particles in a pure substance are exactly the same.substance are exactly the same. Examples – iron, aluminum, water, sugar, Examples – iron, aluminum, water, sugar,

salt.salt.

Elements, cont’dElements, cont’d Element – Def – the simplest pure Element – Def – the simplest pure

substance.substance. Elements can’t be changed into a Elements can’t be changed into a

simpler substance by heating or simpler substance by heating or any chemical process.any chemical process.

The atoms are the smallest The atoms are the smallest particle that a substance can be particle that a substance can be made of and made of and an element has all of an element has all of the same atoms.the same atoms.

Atom – def. – the smallest particle of Atom – def. – the smallest particle of an element that that the properties an element that that the properties of that element.of that element.

Atoms are the basic building block of Atoms are the basic building block of all matter in the UNIVERSE!all matter in the UNIVERSE!

Atoms of the same elements are Atoms of the same elements are alike, atoms of different elements are alike, atoms of different elements are different.different.

Elements, cont’dElements, cont’d

Elements, cont’dElements, cont’d Examples of elements:Examples of elements:

GoldGold AluminumAluminum UraniumUranium IronIron

Scientists decided to create symbols Scientists decided to create symbols for all of the elements in the early for all of the elements in the early 1800’s to make writing the elements 1800’s to make writing the elements easier.easier.

Elements, cont’dElements, cont’d Chemical symbolsChemical symbols are shorthand ways are shorthand ways

of representing the elements. Each of representing the elements. Each symbol consists of one or two letters.symbol consists of one or two letters.

Some element’s symbols come from Some element’s symbols come from their name in English:their name in English: Carbon = CCarbon = C Chlorine = ClChlorine = Cl Aluminum = AlAluminum = Al

Elements, cont’dElements, cont’d Some elements’ symbols come Some elements’ symbols come

from their name in Latin:from their name in Latin: Gold = Aurum = AuGold = Aurum = Au Silver = Argentum = AgSilver = Argentum = Ag Iron = Ferrum = FeIron = Ferrum = Fe Copper = Cuprum = CuCopper = Cuprum = Cu Mercury = Hydragyrum = HgMercury = Hydragyrum = Hg

III. CompoundsIII. Compounds Def. - A pure substance that is Def. - A pure substance that is

made of more than one elementmade of more than one element Made of molecules – 2 or more Made of molecules – 2 or more

atoms bonded togetheratoms bonded together It can be broken down into It can be broken down into

simpler substances – the simpler substances – the elements that make it up.elements that make it up.

Compounds, Compounds, cont’dcont’d Compounds are written as chemical Compounds are written as chemical

formulasformulas that describe the molecules that describe the molecules that make up the compound.that make up the compound.

The The formula is a list of all of the formula is a list of all of the elementselements that make it up that make it up

Elements and their symbols can be Elements and their symbols can be found in the Periodic Table of the found in the Periodic Table of the ElementsElements

Beside each element’s symbol is a Beside each element’s symbol is a number called a number called a subscript – this tells subscript – this tells you how many atoms of that element you how many atoms of that element are in the molecule.are in the molecule.

Compounds, Compounds, cont’dcont’d Examples of compounds:Examples of compounds:

HH22OO CC66HH1212OO66

The small numbers next to the letter The small numbers next to the letter tell you how many of each atom are tell you how many of each atom are in the molecule – in the molecule – those are subscriptsthose are subscripts

6 H6 H22O tells you that there are 6 water O tells you that there are 6 water molecules presents – molecules presents – the 6 is a the 6 is a coefficient – it gives the number of coefficient – it gives the number of molecules in an amount of molecules in an amount of compound.compound.

Compounds, Compounds, cont’dcont’dTo figure out how many atoms of each To figure out how many atoms of each

element are present in a formula:element are present in a formula:1.1. List all the elements in the molecule and do List all the elements in the molecule and do

one element at a time.one element at a time.2.2. If there are parentheses, multiply the If there are parentheses, multiply the

inside subscripts by the outside number. inside subscripts by the outside number. (this is like using the distributive property)(this is like using the distributive property)

3.3. Add all of the subscripts for each element – Add all of the subscripts for each element – sometimes an element will be in 2 places in sometimes an element will be in 2 places in the formula, so you have to add them the formula, so you have to add them together (if there is no subscript, that together (if there is no subscript, that means that there is “1” of that atom.)means that there is “1” of that atom.)

4.4. Multiply all of the totals by the coefficient.Multiply all of the totals by the coefficient.

Compounds, Compounds, cont’dcont’dExample – steps to calculate Example – steps to calculate

3Ca(NO3Ca(NO33))22

Ca, N, OCa, N, O elements listedelements listed

1 Ca, 2 N, 6 O1 Ca, 2 N, 6 O subscripts and subscripts and parentheses calculatedparentheses calculated

1 Ca, 2 N, 6 O1 Ca, 2 N, 6 O like elements added like elements added (no (no change in this case)change in this case)

3 Ca, 6 N, 18 O3 Ca, 6 N, 18 O all totals multiplied by all totals multiplied by the coefficientthe coefficient

Compounds, Compounds, cont’dcont’dList the elements and numbers of each List the elements and numbers of each

element in:element in:

NaClNaCl

NaNONaNO33

4 NH4 NH33

5 C5 C66HH1212OO66

8 Ba(OH)8 Ba(OH)22

CeCe22(SO(SO44))33

5 Cu(NO5 Cu(NO33))22

1 sodium, 1 chlorine

1 sodium, 1 nitrogen, 3 oxygens

4 nitrogens, 12 hydrogens

30 carbons, 60 hydrogens, 30 oxygens

8 bariums, 16 oxygens, 16 hydrogens

2 cesiums, 3 sulfurs, 12 oxygens

5 coppers, 10 nitrogens, 30 oxygens

Chemical EquationsChemical Equations Represent a chemical change (reaction)Represent a chemical change (reaction) Remember that in a chemical change, Remember that in a chemical change,

the substances are changed into new, the substances are changed into new, different substances.different substances.

The substances’ atoms are rearranged.The substances’ atoms are rearranged. A chemical equation shows how the A chemical equation shows how the

atoms changed their “positions”.atoms changed their “positions”.

Chemical EquationsChemical Equations Example – charcoal (carbon) burning in a Example – charcoal (carbon) burning in a

BBQBBQ The chemical sentence would read…The chemical sentence would read… ““Carbon atoms plus oxygen molecules Carbon atoms plus oxygen molecules

produce carbon dioxide molecules”produce carbon dioxide molecules” The chemical equation would readThe chemical equation would read C + OC + O22 COCO22 This equation is read as “1 Carbon plus 2 This equation is read as “1 Carbon plus 2

Oxygens yields carbon dioxide”Oxygens yields carbon dioxide”

Chemical EquationsChemical EquationsC + OC + O22 COCO22

C (carbon) and OC (carbon) and O22 (oxygen) are the (oxygen) are the reactantsreactants – they – they reactreact together to together to create a chemical create a chemical reactionreaction

CO2 is the CO2 is the productproduct – it is what they – it is what they produceproduce

Chemical EquationsChemical Equations C + OC + O22 COCO22 What do you notice about the number of What do you notice about the number of

atoms of each element on either side of the atoms of each element on either side of the arrow?arrow?

HH22 + O + O22 HH22OO What do you notice about the number of What do you notice about the number of

atoms of each element on wither side of the atoms of each element on wither side of the arrow?arrow?

Chemical EquationsChemical Equations HH22 + O + O22 HH22OO

This equation is not equal!!!This equation is not equal!!! On the right and left sides there are 2 hydrogensOn the right and left sides there are 2 hydrogens BUT…on the left there are 2 oxygens and on the BUT…on the left there are 2 oxygens and on the

right, there’s only 1!!!right, there’s only 1!!! Law of chemistry – atoms do not just disappear!! Law of chemistry – atoms do not just disappear!!

THEY NEED TO BE ACCOUNTED FOR!!!!THEY NEED TO BE ACCOUNTED FOR!!!!

Balancing Chemical Balancing Chemical EquationsEquations

HH22 + O + O22 HH22OO

We call this process of accounting for all We call this process of accounting for all of the atoms of the atoms BALANCING EQUATIONSBALANCING EQUATIONS

We balance out the atoms by using We balance out the atoms by using COEFFICIENTSCOEFFICIENTS in front of as many in front of as many molecules as necessary to make sure that molecules as necessary to make sure that the atoms of each element on either side the atoms of each element on either side of the arrow are equal to each other.of the arrow are equal to each other.

Balancing Chemical Balancing Chemical EquationsEquations Steps to balance an equation:Steps to balance an equation:

Check to see if it’s balanced by doing an atom Check to see if it’s balanced by doing an atom count. If it is, stop!count. If it is, stop!

If not, find the most complicated compoundIf not, find the most complicated compound Starting with that compound, go element by Starting with that compound, go element by

element from side to side of the equation, balancing element from side to side of the equation, balancing each element by adding coefficients (“playing each element by adding coefficients (“playing tennis”)tennis”)

Save the “alone” molecules for last as adding a Save the “alone” molecules for last as adding a coefficient to them will not affect any other elementscoefficient to them will not affect any other elements

If an element is repeated on one side of the arrow, If an element is repeated on one side of the arrow, save it for last.save it for last.

Balancing Chemical Balancing Chemical EquationsEquations

HH22 + O + O22 HH22OO

Let’s apply this process to our water Let’s apply this process to our water equation:equation:

Start with HStart with H22O, there are 2 oxygens on O, there are 2 oxygens on the other side of the equation, so add a 2 the other side of the equation, so add a 2 as a coefficient to Has a coefficient to H22OO

HH22 + O + O22 2 H2 H22OO

Balancing Chemical Balancing Chemical EquationsEquations

HH22 + O + O22 2 H2 H22OO

OK, there’s now 2 Oxygens on each side.OK, there’s now 2 Oxygens on each side. But, notice that there are 4 Hydrogens on But, notice that there are 4 Hydrogens on

the right and only 2 on the left.the right and only 2 on the left. So, add a 2 as a coefficient to the HSo, add a 2 as a coefficient to the H22 on on

the left.the left.

2 H2 H22 + O + O22 2 H2 H22OO

Balancing Chemical Balancing Chemical EquationsEquations

2 H2 H22 + O + O22 2 H2 H22OO

OK, are we balanced?OK, are we balanced? 4 Hydrogens on each side4 Hydrogens on each side 2 Oxygens on each side2 Oxygens on each side BALANCED!!! BALANCED!!!

Balancing Chemical Balancing Chemical EquationsEquations Try These…..Try These…..

Mg + HCl Mg + HCl MgClMgCl22 + H + H22 NN22 + H + H22 NH NH33 HH22OO22 H H22O + OO + O22 Al + OAl + O22 Al Al22OO33 HCl + NaOH HCl + NaOH NaCl + H NaCl + H22OO KClOKClO33 KCl + O KCl + O22 Challenges:Challenges: Al + NiBrAl + NiBr22 AlBr AlBr22 + Al + Al22(SO(SO44))33 KCl + Zn(POKCl + Zn(PO44))22 ZnCl ZnCl22 + K + K33POPO44