Download chapter1

CHEMISTRY 161
Chapter 1, p. 1- 39
Chemistry
arabic: al-kimya
greek: khymeia
latin: chimica
‘FUSION’
~ 3,500 BC
Solar System Chemistry
Chemistry in Space
Amino Acids
Sugars
Star Formation
Star Destruction
ASTROBIOLOGY
PROPERTIES OF MATTER
physical
density
color
odor
chemical
EXPERIMENT I
(determine w/o destruction of matter)
reactivity
(determine w/ destruction of matter)
state
CHEMICAL REACTION
EXPERIMENT II
decomposition
(water)
EXPERIMENT III
combination from two or more elements
EXPERIMENT IV
(exception: ozone)
ELEMENTS
1. cannot be decomposed by chemical means
2. different elements have different properties
EXPERIMENT V
3. each element is assigned a unique chemical symbol
(mostly one or two letters)
BOOK
a) first letter is always capitalized
b) all remaining letter(s) are lower case
MATTER
ATOMS
John Dalton
MOLECULES
ELEMENTS
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
Neutron
1.67262 × 10-27 kg
+1.6022 × 10-19 C +1
electron, e 9.10939 × 10-31 kg
-1.6022 × 10-19 C -1
proton, p
neutron, n 1.67493 × 10-27 kg
m(n) / m(e) ≈ 1838
m(n) > m(p)
0
0
Structure of an Atom
subatomic particles
electrons
(‘cloud’)
protons
(nucleus)
neutrons
(nucleus)
neutrons are the ‘glue’ of the nucleus
Atomic Number and Mass Number
mass number
(number of protons plus neutrons)
atomic number
(number of protons)
(number of electrons)
A
Z
X
in an atom, the number of electrons and protons are identical
(charge neutrality)
6 neutrons
12 protons plus neutrons
6 electrons
7 neutrons
6 protons
13 protons plus neutrons
6 electrons
6 protons
12
6
C
13
6
C
elements with same number of electrons and protons but different number of neutrons
ISOTOPES
1
1
3
1
H
2
1
H
H
16
8
1
1
O
12
6
C
H
Periodic Table of the Elements
period
http://www.webelements.com/
g
r
o
u
p
?
Periodic Table of the Elements
8 main groups
10 transition metal groups
lanthanides/actinides
metals
nonmetals
metalloids (semi metals)
metals
metals
metals
– shine, conduct electricity
nonmetals – do not shine, do not conduct electricity
metalloids – properties between metals and nonmetals
Summary
1. What is matter (atoms, molecules, substances, mixtures)
2. Dalton’s postulates
3. Chemical mass scale (amu, u)
4. Building blocks of atoms (electrons, protons, neutrons)
5. Periodic table of the elements