atoms, molecules and ions 1806 atomic theory of matter 1. matter consists of indivisible atoms 2.all...
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Atoms, Molecules and Ions1806Atomic Theory of Matter
1. Matter consists of indivisible atoms
2. All atoms of a given element have identical properties
3. Different elements have atoms that differ in mass
4. Atoms are indestructible and chemical reactions are a rearrangement of atoms
5. Compounds contain a definite and small number of atoms
John Dalton
1. Matter consists of indivisible atoms
subatomic particles 1. electrons2. protons3. neutrons
electrons charge = -1.60 x 10-19 C = -1mass = 9.1 x 10-31 kg
protons charge = +1mass = 1.673 x 10-27 kg
neutrons charge = 0mass = 1.675 x 10-27 kg
1. Matter consists of indivisible atoms
nucleus = protons + neutrons
electrons move around the nucleus
electron “cloud” = volume of atom
average diameter of atom 10-10 m = ångström (Å)
2. All atoms of a given element have identical properties
atoms of an element = same number of protons
atomic number = Z
XZ
elements neutral # e- # protons =
elements different # neutrons
proton + neutron = A = mass number
A
Z = 6 carbon= CZ = 30 = Zn zinc
6C
30Zn6 e-
30 e-
? not exactly
element can have isotopes 7 nuclides of C
carbon Z = 66C
most abundant 6 neutrons12
Carbon-14 dating C6
14
6 protons + neutrons
What is the symbol for a nuclide that contains22 neutrons and 18 protons?
Ar1840
2. All atoms of a given element have identical properties
XZA
8
4. Atoms are indestructible and chemical reactions are a rearrangement of atoms
valence electronsreactionsvalence e- = Group number
12 3 4 5 6 7
8
12 3 4 5 6 7
8
elements arranged by atomic numbercolumn grouprow period
chemical properties
Noble gasesunreactive
monatomic gases
8 valence electrons
Alkali metals
soft solidsvery, very reactive1 valence electron lose 1 electron
Na( protons, e-)1111 Na ( protons, e-)11 10+
cation
(He 2 valence e-)
Alkaline earth metalssolidsreactive2 valence electrons lose 2 electrons
Sr Sr2+
metals non-metals
conduct heat, solids (Hg)
electricity
lose e-
Non-metals
Si 14
C 6B 5 N 7 O 8 F 9
P 15 S 16 Cl 17
As33 Se34 Br35
Te52 I 53
At85
3 4 5 6 7
= metalloids
poor conductorssolids, liquids, gases
Group 7 halogens X2
very reactive
7 valence electrons gain 1 electron
Cl ( protons, e-)17 17 Cl ( protons, e-)17 18-
anion
non-metals gain electrons
H 1 doesn’t fit anywherelose e-
H ( proton, e-)1 1 H ( proton, e-)1 0+
protonH ( proton, e-)1 1 H ( proton, e-)1 2-
hydride
gain e-
5. Compounds contain a definite and small number of atoms Ionic solids
cation + anion+ -
metal non-metal
lithium oxygenLi O+ 2-
+Li O lithium oxide
magnesium nitrogen+
Mg N2+ 3- Mg N magnesium nitride3 2
strong interactions (ion-ion)
sodium chlorineNa Cl+ -
+NaCl sodium chloride
2
high melting points
801o C
> 1700oC
Transition metals
more than 1 form except Ag+
Zn2+
Cd2+
Al3+
aluminum+sulfurAl3+ S2-
Al S2 3
aluminum sulfide
manganese oxygen+Mn1+ Mn2+ Mn3+ Mn4+
Mn4+ O2- MnO2
manganese (IV) oxide
Mn3+ Mn2O3
manganese (III) oxide O2-
Covalent compounds
share valence electrons = chemical bondscarbon + chlorine
C Cl -4+
CCl4
carbon chloridetetra
1 mono2 di3 tri4 tetra5 penta6 hexa7 hepta8 octa
nitrogen + oxygenN O 2-?
NO nitrogen monoxide 2+
NO2 nitrogen dioxide 4+
N2O4 dinitrogen 4+
non-metal + non-metal
tetroxide
Covalent compounds
H
N H1-3+ NH3 nitrogen trihydride ammonia
O2-1+ H2O dihydrogen monoxide water
weak forces low m.p. 0.0oC
Polyatomic ions
NH4+ ClO3
-
Table 2.5 p. 62
ammoniumOH- hydroxideNO3
- nitrateSO4
2- sulfatePO4
3- phosphate
chlorateMnO4
- permanganateCrO4
2- chromateCO3
2-carbonate