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Transcript of Basic Chemistry. The Nature of Matter Matter refers to anything that takes up space and has mass....
Basic ChemistryBasic Chemistry
The Nature of MatterThe Nature of Matter
MatterMatter refers to anything that takes up refers to anything that takes up space and has mass.space and has mass.
Matter is composed of elements, Matter is composed of elements, substances that cannot be broken down substances that cannot be broken down into another substance.into another substance.There are 92 natural elements.There are 92 natural elements.Living organisms are made primarily of six Living organisms are made primarily of six
elements.elements.
The Nature of MatterThe Nature of Matter
The Nature of MatterThe Nature of Matter
Elements:Elements:Made up of tiny particles called Made up of tiny particles called
atomsatomsEach has its own Each has its own
name name atomic number atomic number atomic symbolatomic symbol
Name Number Symbol
Hydrogen 1 H
Aluminum 13 Al
Sodium 11 Na
Atomic StructureAtomic Structure
Atoms have three main sub atomic Atoms have three main sub atomic structuresstructures::
Name Charge Mass LocationName Charge Mass Location
ProtonProton + 1 amu inside nucleus + 1 amu inside nucleus
Electron - 1/1837 amu around nucleusElectron - 1/1837 amu around nucleus
Neutron o 1 amu inside nucleusNeutron o 1 amu inside nucleus
Atomic StructureAtomic Structure
All atoms of the same All atoms of the same element have the same element have the same
number of protonsnumber of protons
It is also equal to the atomic It is also equal to the atomic numbernumber
The Periodic TableThe Periodic Table
The elements are organized to form the The elements are organized to form the periodic tableperiodic table..The columns in the table are groups.The columns in the table are groups.The rows in the table are periods.The rows in the table are periods.
Elements in groups have similar chemical Elements in groups have similar chemical and physical characteristics.and physical characteristics.
The Periodic TableThe Periodic Table
Atomic StructureAtomic Structure
The The Atomic MassAtomic Mass is the number of is the number of
protons and neutronsprotons and neutrons
Na23
11
Mass
Atomic Number
Number of protons: 11
Number of neutrons: 12
(23 – 11)
Number of electrons 11
Composition of Matter- ElementsComposition of Matter- Elements
Symbols to know:Symbols to know:
C Carbon Na Sodium Mg Magnesium C Carbon Na Sodium Mg Magnesium
O Oxygen P Phosphorus Fe Iron O Oxygen P Phosphorus Fe Iron
H Hydrogen S SulfurH Hydrogen S Sulfur Ca CalciumCa Calcium
N Nitrogen Cl Chlorine K PotassiumN Nitrogen Cl Chlorine K Potassium
Composition of Matter- ElementsComposition of Matter- Elements
IsotopesIsotopes
Many elements have isotopes. Many elements have isotopes.
Isotopes have the Isotopes have the same atomic numbersame atomic number
but a but a different atomic massdifferent atomic mass
(they have more or less neutrons)(they have more or less neutrons)
Composition of Matter- ElementsComposition of Matter- Elements
Isotopes are represented differently, showing Isotopes are represented differently, showing their atomic mass.their atomic mass.
Examples: Examples:
carbon – 14carbon – 14 is an isotope of carbon with a is an isotope of carbon with a mass of 14 (the normal mass is 12) mass of 14 (the normal mass is 12)
iodine – 131iodine – 131 is an isotope of iodine with a is an isotope of iodine with a mass of 131 (the normal mass is 127) mass of 131 (the normal mass is 127)
Composition of Matter- ElementsComposition of Matter- Elements
Certain isotopes are very unstable and Certain isotopes are very unstable and release energy as they “fall apart” or release energy as they “fall apart” or disintegrate. disintegrate.
These isotopes are called These isotopes are called radioactive radioactive isotopesisotopes or radioisotopes. or radioisotopes.
This radiation can be detected with a This radiation can be detected with a Geiger counter.Geiger counter.
Uses of Radioactive IsotopesUses of Radioactive Isotopes
Radioactive isotopes can be used as Radioactive isotopes can be used as tracerstracers to follow the movement of that to follow the movement of that element.element.
Radioactive isotopes can be used to Radioactive isotopes can be used to sterilize medical and dental instruments.sterilize medical and dental instruments.
Radioactive isotopes can also be used to Radioactive isotopes can also be used to kill cancer cells.kill cancer cells.
Uses of Radioactive IsotopesUses of Radioactive Isotopes
Atomic StructureAtomic Structure Electrons are found in energy levels outside the Electrons are found in energy levels outside the
nucleusnucleus
The first energy level holds two electronsThe first energy level holds two electrons The second energy level holds eight electronsThe second energy level holds eight electrons
The third energy level holds eight electronsThe third energy level holds eight electrons Other levels can hold moreOther levels can hold more
Octet RuleOctet Rule: Stable atoms have eight electrons : Stable atoms have eight electrons in their outer level in their outer level
Atomic StructureAtomic Structure
Electrons in the outermost shell are called Electrons in the outermost shell are called valence electronsvalence electrons
All elements in the same column (group) All elements in the same column (group) of the Periodic table have the same of the Periodic table have the same
number of valence electronsnumber of valence electronsThe valence electrons determine how an The valence electrons determine how an
element will reactelement will react
Arrangements of Electrons in an Arrangements of Electrons in an AtomAtom
Chemical BondsChemical Bonds
A group of atoms bonded to one another A group of atoms bonded to one another form a form a moleculemolecule..
If the molecule has more than one type of If the molecule has more than one type of element present it is a element present it is a compoundcompound..
Different types of Different types of bondsbonds hold molecules hold molecules and compounds together.and compounds together.
Chemical FormulasChemical Formulas
Types of FormulasTypes of Formulas
Molecular formulas show the actual Molecular formulas show the actual composition of a compound using symbols composition of a compound using symbols
of elements and their proportionsof elements and their proportions
Examples: Examples:
Water Methane Carbon dioxide Water Methane Carbon dioxide
HH22O CHO CH4 4 CO CO22
Chemical FormulasChemical Formulas
Structural formulas are formulas that show Structural formulas are formulas that show the bonding of elements in a compound the bonding of elements in a compound
and their relative positionsand their relative positions
Examples: Examples:
Water Methane Carbon dioxideWater Methane Carbon dioxide
H H OH H O
H C HH C H
H OH O H H C O C O
Composition of Matter - CompoundsComposition of Matter - Compounds
Chemical BondsChemical Bonds
A chemical bond is the “glue” that holds the A chemical bond is the “glue” that holds the elements together in compounds.elements together in compounds.
The valence electrons determine how an The valence electrons determine how an element will react and bondelement will react and bond
Types of Chemical BondsTypes of Chemical Bonds Charged atoms, or Charged atoms, or ionsions, can form when atoms , can form when atoms
lose or gain electrons.lose or gain electrons. Atoms that lose an electron become PositiveAtoms that lose an electron become Positive Atoms that gain electrons become NegativeAtoms that gain electrons become Negative
Positive and negative ions are attracted to one Positive and negative ions are attracted to one another and bond together in another and bond together in ionic bondsionic bonds..
Usually between a metal and non metal that are Usually between a metal and non metal that are far apart horizontally on the periodic table.far apart horizontally on the periodic table.
A A saltsalt is a dry solid composed of atoms is a dry solid composed of atoms connected by ionic bonds.connected by ionic bonds.
Types of Chemical BondsTypes of Chemical Bonds
Ionic Bonds
Sodium (one valence electron)
Loses the electron
Becomes positive (+)
Chlorine (seven valence electrons)
Gains the electron
Becomes negative (-)
Opposites Attract!
Each outer shell has eight electrons
Types of BondsTypes of Bonds
formed when electrons are formed when electrons are sharedshared among among elements in a compound.elements in a compound.
usually formed between two non metals or usually formed between two non metals or a non metal and hydrogena non metal and hydrogen
Models or diagrams can be drawn to show Models or diagrams can be drawn to show the shared electrons the shared electrons
Covalent bondsCovalent bonds
Types of Chemical BondsTypes of Chemical Bonds
Chemical EquationsChemical EquationsEquationsEquations show the: show the:chemicals that are reactingchemicals that are reactingproducts that are madeproducts that are madeamount of each chemical involvedamount of each chemical involved
In equations, In equations, reactantsreactants are on the left are on the left the the productsproducts are on the right. are on the right.
Example:Example:
Water produces hydrogen and oxygenWater produces hydrogen and oxygen
2H2H22O 2HO 2H22 + O + O22
Chemical ReactionsChemical Reactions
Molecules that participate in a reaction are Molecules that participate in a reaction are reactantsreactants..
Molecules formed by a reaction are Molecules formed by a reaction are productsproducts..
6 CO2 + 6 H2O C6H12O6 + 6 O2
carbondioxide
water oxygenglucose
The chemical reaction for photosynthesis
Water, Acids, Bases and pHWater, Acids, Bases and pH
DissociationDissociation occurs when an ionic occurs when an ionic compound separates into its compound separates into its
ions.ions.
Example:Example:Salt (NaCl) breaks apart into Na+ Salt (NaCl) breaks apart into Na+
and Cl-and Cl-
Na+ Cl-
Acids and BasesAcids and Bases
When water dissociates, it releases an When water dissociates, it releases an equal number of ions.equal number of ions.Hydrogen ions (HHydrogen ions (H++))Hydroxide ions (OHHydroxide ions (OH--))
H – O – H H+ + OH-
Water, Acids, Bases and pHWater, Acids, Bases and pH
AcidsAcidsAcids will dissociate in Acids will dissociate in
water to release a water to release a hydrogen ion (H+)hydrogen ion (H+)
Examples:Examples:
HClHCl HH22SOSO44
HCHC33HH55OO33
(Notice the H at the front of the formula)(Notice the H at the front of the formula)
Water, Acids, Bases and pHWater, Acids, Bases and pHBases will dissociate Bases will dissociate
in water and release in water and release OH- (hydroxyl) ionsOH- (hydroxyl) ions
They have a low They have a low concentration of H+concentration of H+
Examples: Examples:
NaOH KOHNaOH KOH(notice they end in –OH)(notice they end in –OH)
pH and the pH scalepH and the pH scale
The The pHpH is a mathematical way of is a mathematical way of indicating the number of Hindicating the number of H++ ions in a ions in a solution. solution.
The lower the number, the higher the The lower the number, the higher the concentration.concentration.
The The pH scalepH scale is used to express acidity or is used to express acidity or basicity (alkalinity).basicity (alkalinity).
Water, Acids, Bases and pHWater, Acids, Bases and pHAcids have a low pH (less than 7) and bases Acids have a low pH (less than 7) and bases
have a high pH (more than 7)have a high pH (more than 7) 1 7 141 7 14
Strong Strong Neutral Neutral StrongStrong
Acid BaseAcid Base
The farther away from neutral, the stronger The farther away from neutral, the stronger the acid or base.the acid or base.
Water, Acids, Bases and pHWater, Acids, Bases and pH
Extremely acidic: Extremely acidic: lemon=2.5; vinegar=3.0; stomach acid=2.0lemon=2.5; vinegar=3.0; stomach acid=2.0 Very strongly acid:Very strongly acid: tomatoes=4.5 tomatoes=4.5 Strongly acid:Strongly acid: carrots=5.0; asparagus=5.5; cabbage=5.3 carrots=5.0; asparagus=5.5; cabbage=5.3 Moderately acid:Moderately acid: potatoes=5.6 potatoes=5.6 Slightly acid:Slightly acid: salmon=6.2; cow's milk=6.5 salmon=6.2; cow's milk=6.5 Neutral:Neutral: saliva=6.6–7.3; blood=7.3; shrimp=7.0 saliva=6.6–7.3; blood=7.3; shrimp=7.0 Slightly alkaline:Slightly alkaline: eggs=7.6–7.8 eggs=7.6–7.8 Moderately alkaline:Moderately alkaline: sea water=8.2; sodium bicarbonate=8.4 sea water=8.2; sodium bicarbonate=8.4 Strongly alkaline:Strongly alkaline: borax=9.0 borax=9.0 Very strongly alkaline:Very strongly alkaline: milk of magnesia=10.5, ammonia=11.1; milk of magnesia=10.5, ammonia=11.1;
Water, Acids, Bases and pHWater, Acids, Bases and pHMixing an acid with a base a chemical Mixing an acid with a base a chemical
reaction will change the pH of the mixturereaction will change the pH of the mixtureHydrogen ions will react with the hydroxyl Hydrogen ions will react with the hydroxyl
ions and form waterions and form water
H H ++ + OH + OH- - HOH HOH If the ions are in equal amounts, the If the ions are in equal amounts, the
mixture becomes neutral (pH 7)mixture becomes neutral (pH 7)This is called a This is called a neutralizationneutralization reaction. reaction.The remaining ions form a salt.The remaining ions form a salt.
Buffers and pHBuffers and pH
Within the body, the pH is kept in a narrow Within the body, the pH is kept in a narrow range to maintain health. range to maintain health.
A A bufferbuffer is a chemical or combination of is a chemical or combination of chemicals that keeps a pH within a given chemicals that keeps a pH within a given range. range.
Buffers resist changes in pH by taking up Buffers resist changes in pH by taking up extra Hextra H++ or OH or OH-- from solution. from solution.
Buffers and pHBuffers and pH