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Scientific Method Steps 1-3
Sta
te t
he
Pro
ble
m1. QuestionMake it as precise as possible
2. HypothesisTestable Prediction
3. ExperimentIndependent Variable: I change itConstant always keep it the sameControl Group: Compare all your tests to this groupPredict ObserveThink
Scientific Method Steps 4-64. DataDependent VariableDepends on the Independent variable
Qualitative means describe or categorize
Quantitative means a measure a number
5. ConclusionsDoes the Data support the hypothesis?If no, revise the hypothesisIf yes, thenTheory = happens more than onceLaw = happens ALL the time
6. CommunicateEnough detail to allow others to repeat experiment
Infer
Compare & Contrast
Classify
SolidLow EnergyAtoms tightly stucktogether
LiquidMedium EnergyAtoms loosely stucktogether
GasHigh EnergyAtoms not stucktogether
PlasmaHighest EnergyAtoms not stucktogether
Freezin
gMelting
Relaxation
Condensa
tion
Ionization
Eva
pora
tion
_Melting Point
Boiling Point Dew Point
Freezing Point
States of Matter
States of Matter: Big Ideas Plasma- freely moving molecules, free electrons
Gas-freely moving molecules
Liquid-loosely packed
Solid- tightly packed
Pure Substances
Made of one type of matter
ElementsMade of one type of atom
CompoundsMade of 2 or
More atoms bondedtogether
Homogeneousone phase
MATTERMade of AtomsHas Mass &
takes up Space
HeterogeneousMade of more than one phase
Can be separated
MixturesMade of
more than one type of matter
SoluteThe stuff that is
dissolvedIn the liquid
Ex: Kool-Aid mix
Atom + Atom = Molecule
Molecule+Molecule = ELEMENT Molecule + Molecule
= COMPOUND
SolutionAll its regions are
IdenticalEx: Kool-Aid
SolventThe liquid that
forms the solutionEx: Water
Examples:Trail Mix
Salad
Atom + Atom = Molecule
CharacteristicsColorShapeSize
TextureMass
VolumeDensity
PhysicalProperties
Describe a Substance
ChemicalProperties
Describe how it can form a new substance
Changes of StateMeltingFreezingBoiling
CondensationIonizationRelaxation
StatesSolidLiquidGas
Plasma
Properties of Matter
PropertiesFlammability
ReactivityToxicity
Signs of Chemical Reaction
Color ChangeTemp
changeBubbles
Solid FormationOdor
Matter BIG IDEAS
Pure Substances
Elements: one type of Atom (Ex: Al Foil)
Compounds: 2 or more atoms bonded together (Ex: H2O)
Mixtures more than one type of matter
States Solid
Liquid
Gas
Plasma
Physical Properties
Describe a substance ( color size, shape)
Chemical Properties
Describe how it can make a new substance (flammable)
Signs of Chemical Reaction
Color Change
Temp change
Bubbles
Solid Formation
Odor
ATOMS = Building Blocks of MatterMOLECULE = 2 or more atoms bonded together. Ex: NaCl, H2O, CH4, H2
Atomic Structure
Sub-atomic particle
Location Charge Mass
Proton Nucleus +1 1
Neutron Nucleus 0 1
Electron Orbiting the nucleus
-1 0
Atomic #Proton#Electron#SAME
Bohr Model of the Atom
Electrons are arranged in fixed orbits around the nucleus.
fill up orbits in order from lowest energy (inside orbit) to highest energy (outside orbits).
Electrons are arranged in a fixed orbit in 2, 8, 8, 8.
Bohr model only works up to atomic number20 (Ca)
Valence Electrons
Valence Electrons = #electrons in outer orbit
Atoms are “HAPPY” when they have a full valence orbit.
They will find another atom to exchange or share electrons so they have a full valence orbit
1 Valence Electron
Chemical Bonding
Atoms are “HAPPY” when they have a full valence orbit.
They will find another atom to exchange or share electrons so they have a full valence orbit.
Atomic Structure BIG IDEAS sub-atomic particles
Protons (+), Neutrons(0) in Nucleus
Electrons (-) in orbits
APES = Atomic # Proton# Electron# SAME
Bohr Model: Fixed orbits 2, 8, 8, 8
electrons
Works up to Ca (#20)
Valence Electrons: = electrons in outer orbit
Atoms are “HAPPY” when they have a full valence orbit.
They will find another atom to exchange or share valence electrons so they have a full valence orbit
1 Valence Electron
Types of chemical bonds: Ionic
• Metals to Non-metals,• Metals give electrons, Non-metals take electrons. • Metals =positive ions, • Nonmetals =negative ions.
Types of chemical bonds: Covalent
• non-metals to non-metals, share valence electrons, • 50% custody of electrons • EXCEPT for water which has polar covalent • Electrons spend more time with oxygen ( O =- side of molecule H = + side of molecule).
Types of chemical bonds: Metallic
• non-metals to non-metals, share valence electrons, • 50% custody of electrons • EXCEPT for water which has polar covalent • Electrons spend more time with oxygen ( O =- side of molecule H = + side of molecule).
Types of Bonds BIG IDEASAtoms Bond using Valence Electrons TO BE HAPPY
Bond Type
Partner #1
Partner #2
What Happens
Who does what
In the End
IONIC Metal NonMetal
Transfer Electrons
Metal GivesNonmetal Takes
METAL = + IonNONMETAL = - Ion
COVALENT
Nonmetal or H
Nonmetal
Share electrons between 2 atoms
Both share valence electrons EQUALLY
Joint Custody
METALLIC
Metal Metal Share electrons between ALL atoms
All share valence electrons
Sea of Electrons
Periodic Table BIG IDEAS
organized in
columns= Groups & rows= Periods Ones digit of group # = # of valence electrons
Period#= tells us the last orbit which # is filled with valence electrons
Zig-zag Line divides Metals & Nonmetals
Representing bonds: Bohr Model of Valence Electrons
We do this to figure out how many atoms will bond with each other when forming compounds.
Representing bonds: Lewis dots
We do this to figure out how many atoms will bond with each other when forming compounds.
Representing bonds: Oxidation #
1. Find the oxidation numbers for each element from the periodic table. 2. Write the number above & to the right of each element (it’s a superscript). 3. Criss-cross the numbers without the sign: the superscript for each element becomes the subscript for the other element.
Bonding BIG IDEAS
Bohr Model & Lewis Dots work only up to Ca (atomic #20)
Oxidation Numbers (crisscross) work for ALL elements
The crisscross tells us how many atoms bond to make a HAPPY molecule
Then we write the Balanced equation to make it happen
Balancing Equations
Must obey Law of Conservation of Mass1. # of reactant atoms = # of product atoms for each type
of atom
2. You CAN ONLY CHANCE THE COEFFICIENT, NOT THE SUBSCRIPT!
Balancing Tips
Subscripts These are the numbers below the symbol
They tell how many atoms are bonded together in one molecule
For example C2H6 has 2C atoms bonded to 6H atoms
The subscripts are determined by the valence electrons
WE CAN’T CHANGE THE SUBSCRIPT!!
We find the subscripts by using:
Bohr Model
Lewis Dots
Criss-cross /oxidation #
HH
C C H
HH
H
Balancing tips
Coefficients These are the numbers in front of the symbol
They tell how many atoms or molecules we have
It multiplies the number of atoms or molecules (including the subscript)
Ex: 3Na = 3Na atoms
2 C2H6 = 2x2 = 4C atoms
=2x6 = 12H atomsIT IS THE ONLY NUMBER THAT
WE CAN CHANGE!!
Balancing BIG IDEAS
The crisscross tells us how many atoms bond to make a HAPPY molecule
Then we write the Balanced equation to make it happen
Must obey Law of Conservation of Mass
# of reactant atoms must = # of product atoms for each type of atom
CAN ONLY CHANCE THE COEFFICIENT, NOT THE SUBSCRIPT!
Types of reactions
decomposition (break apart)
2H2O2 + yeast 2H2 + 2O2
synthesis (put together)
2H2 +O2 2H2O
combustion (fire) CH4 + O2(g) CO2(g) + 2H2O(g)
single replacement (one pushes the other out)
Zn(s) + HCl (aq) ZnCl2(aq) +H2 (s)
double replacement (the two switch) PbI(aq) + K(NO3)(aq) K(NO3)(aq) + PbI(s)
Chemical Reactions BIG IDEAS
We want to PREDICT what happens when things react:
1. The type of reaction allows us to predict what type of chemical reaction will occur and the products;
2. Then, the crisscross tells us how many atoms bond to make a HAPPY molecule in the products;
3. Then we write the Balanced equation to make it happen
Doing Chemistry EXAMPLE• What happens when I put a piece of Zn in HCl?
• Zn + HCl ???
1. Type of reaction MUST be Single replacement:
• Zn + HCl ZnCl? +H2
• The crisscross tells us the formula is ZnCl2 and that little H will find a buddy
• The BALANCED equation is:
• Zn + 2HCl ZnCl2 +H2
Aqueous Solutions Water has superpowers
because it forms a polar covalent bond (unequal sharing of the electrons)
This allows water to surround and separate many compounds.
Acids & bases can only form in water Acids: Forms H+ ions (steal
electrons) when dissolved in water
Bases: Release OH- ions (force to take electrons) when dissolved in water
H+ OH-
pH Scale
Measures whether a substance is an acid or a base.
pH scale goes from 0-14
pH <7 =acidic
pH =7 =neutral (pure water)
pH >7 = bases
Aqueous Solutions BIG IDEAS
Water is a polar molecule
which has superpowers
Most of chemistry happens in Aqueous solutions
Acids & bases can only form in water Acids: Forms H+ ions (steal electrons)
Bases: Forms OH- ions (force to take electrons)
pH scale goes from 0-14
pH <7 =acidic
pH =7 =neutral (pure water)
pH >7 = bases
H+
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