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.