chapter 4 p. 85 - 109 mixtures, elements and compounds
TRANSCRIPT
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