Basic Chemistry
Chemistry Warm-Up
a. Compound
b. Molecule
c. Proton
d. Neutron
e. Electron
f. Ion
g. Isotope
h. Atom
i. Element
j. Nucleus
1. negatively charged sub-atomic particle
2. A charged particle
3. Positively charged sub-atomic particle
4. Contains protons and neutrons
5. 2 or more atoms bonded together
6. Atoms of different elements bonded together
7. Neutral sub-atomic particle
8. Atoms with equal # of protons, but different # of neutrons
9. The smallest particle of an element
10. Substance composed of 1 type of atom
Matching Answers
a. Compound - Atoms of different elements bonded together (6)b. Molecule - 2 or more atoms bonded together (5)c. Proton - Positively charged sub-atomic particle (3)d. Neutron - Neutral sub-atomic particle (7)e. Electron - negatively charged sub-atomic particle (1)f. Ion - A charged particle (2)g. Isotope - Atoms with equal # of protons, but different # of
neutrons (8)h. Atom - The smallest particle of an element (9)i. Element - Substance composed of 1 type of atom (10)j. Nucleus - Contains protons and neutrons (4)
Atom – the smallest unit of matter “indivisible”
Heliumatom
Contains 3 sub-atomic particlesProtons ( p+): Mass = 1Neutrons (N0): Mass = 1Electrons (e-): Mass = 0
Atom
Atomic Number - # of protons in an atom
Atomic Mass - # of protons and neutrons in an atom.
C6
Carbon
12.001
Atomic #
Atomic massChemical Symbol
Learning Check• Look at your Periodic Table and determine
the number of protons, neutrons, and electrons for the following atoms:• Nitrogen
• Lithium
• Hydrogen
• Fluorine
What are living things made of?
Why do we need these?
These atoms make up the molecules of life. Many act as vitamins and minerals, help our cells carry out important reactions.
Isotopes – Who Cares?!
• Same # protons (same element, same exact chemical behavior)
• different # neutrons
• Some isotopes are radioactive – Nucleus is unstable. Spontaneously gives off energy (radiation)
Isotopes
• Medical Uses• Tracers and Labels
• Ex: Iodine 131 – Behaves exactly like I127. Moves through human body and accumulates in thyroid. Half-life of 8 days. Gives off energy, so presence can be detected.
• Ex: PET scan
Isotopes• Half-Life: Time it
takes for ½ atoms in a sample to decay
• Can be used to determine age of rocks, fossils, etc.
• Carbon-14 is radioactive. ½ Life = 5,730 years.
Electron Shellsa) Atomic number = number of Electrons
b) Electrons vary in the amount of energy they possess, and they occur at certain energy levels or electron shells.
c) Electron shells determine how an atom behaves when it encounters other atoms
Electrons are placed in shells according to rules:
1) The 1st shell can hold up to two electrons, and each shell thereafter can hold up to 8 electrons.
2) “The Octet Rule”: Atoms will gain or lose electrons in order to have a filled outer shell. (Most stable state)
Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons
C would like to N would like toO would like to
Gain 4 electronsGain 3 electronsGain 2 electrons
Predict: How many electrons will these atoms lose/gain?
Why are electrons important?1) Elements have different electron configurations
different electron configurations mean different levels of bonding (and different chemical properties)
Electron Dot StructuresSymbols of atoms with dots to represent the valence-shell electrons
1 2 13 14 15 16 17 18
H He:
Li Be B C N O : F :Ne :
Na Mg Al Si P S :Cl :Ar :
Learning Check A. X would be the electron dot formula for
1) Na 2) K 3) Al
B. X would be the electron dot formula
1) B 2) N 3) P
Dmitri Mendeleev
The Periodic Table of the Elements
The Periodic Table• A map of the building block of matter.
1IA
18VIIIA
11H
1.00797
2IIA
Periodic Table 13IIIA
14IVA
15VA
16VIA
17VIIA
2He
4.0026
23
Li6.939
4Be
9.0122
5B
10.811
6C
12.0112
7N
14.0067
8O
15.9994
9F
18.9984
10Ne
20.179
311
Na22.9898
12Mg24.305
3IIIB
4IVB
5VB
6VIB
7VIIB
8 9VIIIB
10 11IB
12IIB
13Al
26.9815
14Si
28.086
15P
30.9738
16S
32.064
17Cl
35.453
18Ar
39.948
419K
39.102
20Ca40.08
21Sc
44.956
22Ti
47.90
23V
50.942
24Cr
51.996
25Mn
54.9380
26Fe
55.847
27Co
58.9332
28Ni58.71
29Cu63.54
30Zn65.37
31Ga65.37
32Ge72.59
33As
74.9216
34Se78.96
35Br
79.909
36Kr83.80
537
Rb85.47
38Sr87.62
39Y
88.905
40Zr91.22
41Nb
92.906
42Mo95.94
43Tc[99]
44Ru
101.07
45Rh
102.905
46Pd106.4
47Ag
107.870
48Cd
112.40
49In
114.82
50Sn
118.69
51Sb
121.75
52Te
127.60
53I
126.904
54Xe
131.30
655Cs
132.905
56Ba
137.34
57La
138.91
72Hf
178.49
73Ta
180.948
74W
183.85
75Re186.2
76Os190.2
77Ir
192.2
78Pt
195.09
79Au
196.967
80Hg200.59
81Tl
204.37
82Pb
207.19
83Bi
208.980
84Po[210]
85At[210]
86Rn[222]
787Fr[223]
88Ra[226]
89Ac[227]
104Ku[260]
105 106 107 108 109http://www.chemsoc.org/viselements/pages/periodic_table.html
Layout of the Periodic Table: Metals vs. nonmetals
1IA
18VIIIA
12
IIA13
IIIA14
IVA15VA
16VIA
17VIIA
2
33
IIIB4
IVB5
VB6
VIB7
VIIB8 9
VIIIB10 11
IB12IIB
4
5
6
7
MetalsMetalsNonmetalsNonmetals
Across the Periodic TablePeriods: Horizontal rows (1-7)These elements have the same number of valence shells.
1IA
18VIIIA
12
IIA13
IIIA14
IVA15VA
16VIA
17VIIA
2
33
IIIB4
IVB5
VB6
VIB7
VIIB8 9
VIIIB10 11
IB12IIB
4
5
6
7
2nd Period
4th PeriodAll of these have 4 energy levels
Down the Periodic Table•Family: Are arranged vertically down the periodic table (columns or group, 1- 18 or 1-8 A,B)•These elements have the same number of valence electrons
1IA
18VIIIA
12
IIA13
IIIA14
IVA15VA
16VIA
17VIIA
2
33
IIIB4
IVB5
VB6
VIB7
VIIB8 9
VIIIB10 11
IB12IIB
4
5
6
7
Alkali Family: 1 e- in the valence shell
Alkali Family: 1 e- in the valence shell
Halogen Family: 7 e- in the valence shell
Halogen Family: 7 e- in the valence shell
AlkaliHalogen
Periodic Table: electron behavior• Elements in the periodic table can be classified by the behavior of their electrons
1IA
18VIIIA
12
IIA13
IIIA14
IVA15VA
16VIA
17VIIA
2
33
IIIB4
IVB5
VB6
VIB7
VIIB8 9
VIIIB10 11
IB12IIB
4
5
6
7
West (South) Mid-plains East (North)METALS
AlkaliAlkaline
Transition
METALLOID NON-METALSNoble gasHalogensCalcogens
These elementstend to give up
e- and formCATIONS
These elementswill give up e- or
accept e-
These elementstend to accept
e- and formANIONS
Metals Metaloids Non-Metals
Learning Check
A. Number of valence electrons in aluminum1) 1 e- 2) 2 e- 3) 3 e-
B. Change in electrons for octet1) lose 3e- 2) gain 3 e- 3) gain 5 e-
C. Ionic charge of aluminum 1) 3- 2) 5- 3) 3+
Atomic Bonding
• Atoms can form several types of bonds• Covalent
• Ionic
• Hydrogen
• Molecules - Atoms covalently bonded together • Compounds – Atoms of different
elements bonded together
Ionic Bond• Between metals and nonmetals
• Bond formed by transfer of electrons
• Produce charged ions
• Examples; NaCl, CaCl2, K2O
1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.
Covalent Bond
• Between 2 nonmetals
• Formed by sharing electron pairs
• Examples; O2, CO2, C2H6, H2O, SiC
I want more electrons
No I want more
electrons!
Let’s share
2. Covalent bonds- Two atoms share one or more pairs of outer-shell electrons.
Oxygen Molecule (O2)
Water Molecule (H2O)Water Molecule (H2O)
There are other ways of representing covalent bonds.
Quick Check Question• For each of the following element pairs,
determine whether a covalent bond or an ionic bond is likely to form.
• K and S
• Be and F
• Li and I
• O and O
Any Questions? • Next we will make some paper molecules.
Each group will make a different molecule or compound so that we can see a variety.
• CO2, H2O, CH4, O2, N2, NH3, H2, LiF, HCl• Step 1: Determine the type of bond in each
molecule/compound• Step 2: Cut out the atoms and electrons you
will need and glue them onto construction paper
• Color and label
when electrons are shared equally
NONPOLAR COVALENT BONDS
H2 or Cl2
2. Covalent bonds- Two atoms share one or more pairs of valence electrons.
Oxygen Molecule (O2)
Aside from single covalent bonds, double, or triple covalent bonds can form.
A double bond… how many electrons are shared?
4e-
A triple bond…. How many electrons here? 6e-
when electrons are shared but shared unequally
H2O
POLAR COVALENT BONDS
- water is a polar molecule because oxygen is more electronegative than hydrogen, and therefore electrons are pulled closer to oxygen.
Hydrogen Bonds
Partially charged ends of polar molecules are attracted to neighboring molecules. Gives water its special properties.
Water and Living Things • Water is the most abundant molecule in
living things.
• Water has special traits that make it important to life.
Properties of Water
• Hydrogen bonding between polar molecules causes water to “stick together”
• Adhesion• Cohesion• Capillary Action• Surface Tension• Excellent Solvent• High Specific Heat • Frozen water is less dense so ice floats
Properties of Water
Adhesion
Cohesion
Surface Tension
Capillary action helps carry water to the tops of tall trees
Water expands as it freezesWhy is this important for life?
Ice Water Steam
Water as a Solvent
Chemical Reactions• Involves making and breaking chemical
bonds• Necessary for cells
• Build molecules for growth and maintenance• Store/release energy• metabolism
Chemical Reactions• Forming and breaking of bonds.
• Necessary for cells• Build molecules for growth and maintenance
• Store/release energy
Reactants Products
Breakdown of H2O:
2H2O 2H2 + O2
Photosynthesis:
6H2O + 6CO2 C6H12O6 + 6O2
Electrical energy
Light energy
Balanced equations: represents conservation of matter!
Ions
• Salts dissociate in water – result is ions
• NaCl Na+ and Cl-
• Polar H2O molecules attract, dissolve ions
pH• Ionization: non-polar
molecules are converted to ions
H2O H+ and OH-
• In a sample of water, a small percent of molecules are always ionized
pH• Levels of H+ and OH in solution rated using
pH scale.
• Equal H+ and OH- pH of 7 (ex: pure water)
• Logarithmic scale – each level has 10x more H+ or OH- than previous
• Acids are molecules that release hydrogen ions in solution.
HCl H+ + Cl-
• Bases are molecules that either take up hydrogen ions or give off hydroxide ions in solution.
NaOH Na+ + OH-
• Water dissociates and releases hydrogen ions (H+) and hydroxide ions (OH-).
An equal number of H+ and OH-So that’s why water is neutral!
pH• Crucial to living things.• Enzyme Function• Acidic stomach, Alkaline intestine• Blood pH = 7.4• Buffers in living things help resist pH change
• Buffers are substances that help to resist change in pH.