CHEMISTRY 161

Chapter 1, p. 1- 39

Chemistryarabic: al-kimya greek: khymeia

latin: chimica

‘FUSION’~ 3,500 BC

Solar System Chemistry

Chemistry in Space

Star Formation Star Destruction

Amino Acids Sugars

ASTROBIOLOGY

PROPERTIES OF MATTERphysical chemical

densitycolorodor

(determine w/o destruction of matter)

reactivity

(determine w/ destruction of matter)

CHEMICAL REACTIONstate

EXPERIMENT I

EXPERIMENT II

decomposition (water)

combination from two or more elements

(exception: ozone)

EXPERIMENT III

EXPERIMENT IV

ELEMENTS

1. cannot be decomposed by chemical means

2. different elements have different properties

3. each element is assigned a unique chemical symbol (mostly one or two letters)

a) first letter is always capitalizedb) all remaining letter(s) are lower case

EXPERIMENT V

BOOK

MATTER

ATOMS

MOLECULES

ELEMENTS

John Dalton

matter is composed of

‘building blocks’

Dalton’s postulates

1. Elements are composed of small particles called atoms;atoms of an element are identical with same properties (mass)

2. Compounds are composed of atoms of more than one element; in a compound, the ratio of the number of atoms is an integer or fraction

LAW OF DEFINITE PROPORTIONS

3. A chemical reaction involves separation and combination of atoms; atoms are neither created nor destroyed

an atom is the basic, undividable unit of any element

1. Law of definite proportions

2. Law of conservation of mass

in a chemical reaction

no gain or loss of mass is observed

unit of mass is g (gram) or kilogram (kg)one pound is 453.6 g

each atom has a constant mass

atomic mass – atomic weight

CHEMICAL MASS SCALE

standard / calibration

atomic mass unit (amu, u)

one atom of carbon-12 12 u (exactly)

Structure of an Atom

subatomic particles

electrons

protons neutrons

proton,p 1.67262 × 10-27 kg +1.6022 × 10-19 C +1

electron,e 9.10939 × 10-31 kg -1.6022 × 10-19 C -1

m(p) / m(e) ≈ 1836

the atom’s positive charge is located in a small, dense central core ‘nucleus’

protons are a constituent of the nucleus

+ ++ +

+

1. mass of the nucleus constitutes most of the mass of the atom

2. the nucleus is positively charged and contains protons

3. the nucleus constitutes only about 1/1013 space of an atom

4. electrons are as clouds around the nucleus

proton, p 1.67262 × 10-27 kg +1.6022 × 10-19 C +1

electron, e 9.10939 × 10-31 kg -1.6022 × 10-19 C -1

neutron, n 1.67493 × 10-27 kg 0 0

Neutron

m(n) / m(e) ≈ 1838

m(n) > m(p)

Structure of an Atom

subatomic particles

electrons(‘cloud’)

protons(nucleus)

neutrons(nucleus)

neutrons are the ‘glue’ of the nucleus

Atomic Number and Mass Number

AZXatomic number

(number of protons)

(number of electrons)

mass number

(number of protons plus neutrons)

in an atom, the number of electrons and protons are identical (charge neutrality)

136C

6 electrons 6 protons

12 protons plus neutrons6 neutrons 126C

13 protons plus neutrons7 neutrons

6 electrons 6 protons

elements with same number of electrons and protons but different number of neutrons

ISOTOPES

11H

31H

21H

168O

11H

126C

Periodic Table of the Elements

period

group

http://www.webelements.com/

?

Periodic Table of the Elements

8 main groupsmetals

nonmetalsmetalloids (semi metals)

metals – shine, conduct electricitynonmetals – do not shine, do not conduct electricitymetalloids – properties between metals and nonmetals

10 transition metal groups

lanthanides/actinides

metals

metals

Summary

1. What is matter (atoms, molecules, substances, mixtures)

4. Building blocks of atoms (electrons, protons, neutrons)

5. Periodic table of the elements

2. Dalton’s postulates

3. Chemical mass scale (amu, u)