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INTRO TOINTRO TOCHEMISTRYCHEMISTRY
Biology I
MatterMatter Anything that occupies spaceoccupies space and has
massmass.
Examples:Examples:
1.1. rockrock
2.2. woodwood
3.3. metalmetal
4.4. airair
Matter is divided into 3 states
Solids have both a definite volume & definite shape (rock)
Liquids have a definite volume but no definite shape; they can be poured (water)
Gases do not have a definite volume or definite shape, but they take the volume & shape of their container
Matter consist of atoms, which are the smallest unit of matter that can’t be
broken down.
Most atoms consist of 3 particles:Electrons---Protons---Neutrons
Components of anComponents of an AtomAtom
ComponentComponent Charge Charge LocationLocation
1.1.ProtonProton positivepositive nucleus nucleus
2.2.NeutronNeutron neutralneutral nucleus nucleus
3.3.ElectronElectron negativenegative around the around the nucleusnucleus
Atoms
The simplest particle of an element that retains all the properties of that element
Properties of atoms determine the structure and properties of the matter they compose
Our understanding of the structure of atoms based on scientific models not observation
The Nucleus
Central core Consists of positive
charged protons and neutral neutrons
Positively charged Contains most of the
mass of the atom
The Protons
All atoms of a given element have the same number of protons
Number of protons called the atomic number Number of protons balanced by an equal
number of negatively charged electrons
The Neutrons
The number varies slightly among atoms of the same element
The Electrons
Negatively charged high energy particles with little mass
Travel at very high speeds at various distances (energy levels) from the nucleus
Chemical ElementsChemical Elements
ElementsElements are pure substances which cannot are pure substances which cannot be chemically broken down into simpler be chemically broken down into simpler kinds of matter.kinds of matter.
More than 100 elements have been More than 100 elements have been identified, but only about 30 are important identified, but only about 30 are important in living things in living things
All of the Elements are arranged on a chart All of the Elements are arranged on a chart known as the known as the Periodic TablePeriodic Table
Periodic charts tell the atomic number, Periodic charts tell the atomic number, atomic mass, & chemical symbol for every atomic mass, & chemical symbol for every element element
Four elementsFour elements, Carbon – C, Hydrogen – H, , Carbon – C, Hydrogen – H, Oxygen – O, and Nitrogen – N make up Oxygen – O, and Nitrogen – N make up almost 90% of the mass of living thingsalmost 90% of the mass of living things
Chemical Elements Chemical Elements cont..cont..
Each element has an unique chemical symbol Consists of 1-2 letters First letter is always capitalized
The number of protons in an atom is called the atomic number & determines which element it is.
The number of protons & neutrons is called the atomic mass or mass #.
How do we find the #of neutrons?
Atomic mass (# of neutrons & protons)
- Atomic # (# of protons)
= # of neutrons
10
12835
ELECTRONS The number of positively charged protons is
balanced by an equal number of negatively charged electrons (e-).
Electrons at outer levels have more energy than those in inner levels.
Each level or shell can only hold a certain # of e- The first level, nearest the nucleus can only hold
two electrons, the second and other outer levels can hold up to eight electrons each.
A stable atom is an atom that has a full outer level
Electrons in the same energy level are approximately the same distance from the nucleus
Outer energy levels have more energy than inner levels
Each level holds only a certain number of electrons
A T O M S
CompoundCompound
Substance containing two or more two or more elementselements.
Example:Example: CC66HH1212OO66 (glucose - (glucose -
sugar)sugar)
6 - carbons6 - carbons
12 - hydrogen12 - hydrogen
6 - oxygen6 - oxygen
Question:Question:
Answer the following questions aboutAnswer the following questions about CC66HH1212OO66
1. How many elementselements are involved?
2. How many atomsatoms are involved?
Answer:Answer:
11. ElementsElements - - 3 (C, H, O)3 (C, H, O)
2. 2. AtomsAtoms - - 2424
AtomAtom
The smallest unit of mattersmallest unit of matter that still retains the properties of an elementelement.
Carbon - AtomCarbon - Atom
Protons Protons - 6- 6
NeutronsNeutrons - 6- 6
Electrons- 6Electrons- 6
Atomic NumberAtomic Number
EqualsEquals the number of protonsnumber of protons within the nucleus of an element.
Examples:Examples:
Hydrogen (H)Hydrogen (H) - 1- 1
Sodium (Na)Sodium (Na) - 11- 11
Carbon (C)Carbon (C) - 6- 6
Oxygen (O)Oxygen (O) - 8- 8
Gold (Au)Gold (Au) - 79- 79
Atomic MassAtomic Mass
EqualsEquals the number of protons + neutronsprotons + neutrons.
Examples:Examples:
Hydrogen (H)Hydrogen (H) - 1.0079- 1.0079
Sodium (Na)Sodium (Na) - 23- 23
Carbon (C)Carbon (C) - 12- 12
Oxygen (O)Oxygen (O) - 16- 16
Gold (Au)Gold (Au) - 197- 197
Charge of an ElementCharge of an Element Question:Question: protonsprotons = electronselectrons
Answer:Answer: charge is neutralneutral
Question:Question: protons protons electronselectrons
Answer:Answer: the charge is either either negativenegative or or positivepositive
IsotopeIsotope AtomsAtoms of elements with different
number of neutronsneutrons.
Examples:Examples:
carbon - 12carbon - 12
carbon - 13carbon - 13
carbon - 14carbon - 14
Isotopes of CarbonIsotopes of Carbon
NucleusNucleus 1212CC 1313CC 1414CC
protonsprotons 66 66 66
neutronsneutrons 66 77 88
electronselectrons 66 66 66
ElectronsElectrons orbit around the nucleusnucleus
first bonding orbital - 2 electrons2 electrons
all other bonding orbitals - maximum 8 electronsmaximum 8 electrons
orbitals have certain energy levelsenergy levels
orbitals farther from the nucleus have the highest
energy level.
Sodium and Chlorine – Sodium and Chlorine – Electrons Bonding OrbitalsElectrons Bonding Orbitals
NaNa ClCl
Chemical BondingChemical Bonding ThreeThree types of bondsbonds with different different
strengthsstrengths:
covalent > ionic > hydrogencovalent > ionic > hydrogen
Covalent BondsCovalent Bonds strongest bondstrongest bond two elements shareshare one or more pairsone or more pairs
of outer electrons singlesingle and double bondsdouble bonds Examples:Examples:
1. H2O (water - polar molecule)
2. CH4 (methane)
3. O2 (dioxide)
O-
H+
H+
O=O
H-C-HH
H
IonIon atom or molecule with an electric electric
chargecharge.
resulting from a gain or loss of one or gain or loss of one or more electronsmore electrons.
Examples:Examples:
Sodium ion (NaSodium ion (Na++))
Chloride ion (ClChloride ion (Cl--))
Ionic BondsIonic Bonds second strongest bondsecond strongest bond
two ions with opposite charges two ions with opposite charges attract to each other.attract to each other.
Examples:Examples:
salts (NaCl)salts (NaCl)
acidsacids
basesbases
Ionic BondIonic Bond Example:Example: salt (Nasalt (NaCl)Cl)
ClClNaNa
Hydrogen BondingHydrogen Bonding weakest of the three bonds.weakest of the three bonds. Most important and common of all Most important and common of all
bonds.bonds. Partially positive hydrogenPartially positive hydrogen atom of one
molecule is attracted to the partially partially negative atom negative atom of another molecule (O or (O or N).N).
Example:Example: HH22OOO-O-
H+
H+
H+ H+H+ O-
H+
H+ O-
H+
hydrogen bonds