Chemistry Lecture Slide Week 1

Contents:
• Types of Matter
• Atoms & Atomic Theory
• Atomic Masses
• Naming Compounds
• Mole Concept

• MatterMatter is anything that has mass and occupies space.
• It exist in 3 phases:
 Solid – fixed shape and volume.
 Liquid – fixed volume & not rigid in shape (shape of the
container).
 Gas – neither fixed volume nor a rigid shape (depend on
the volume and shape of the container)
• Matter can be classified into two categories:
 Pure substance – fixed composition and unique set of
properties.
 Mixtures – composed two or more substances.

Elements
• A type of matter that cannot be broken down into 2 or
more pure substance.
• consists of only one kind of atoms. All atoms of a given
element are identical, having the same size, mass and
chemical properties.
• The atoms of one element are different from the atoms
of all other elements – each elements is unique.
• Example:
 Copper (Cu) – use in electrical wiring, jewelry, water
pipe.
 Aluminium (Al) – household utensils

Compound
• Pure substance that composed of two or more
different elements that are chemically bound
together.
 Example: Water contain oxygen (O) and hydrogen (H).
• Compounds have fixed compositions – always contain
the same elements in the same percentages by mass.
 Water contain precisely 11.19% hydrogen and 88.81%
oxygen.
• The properties of compounds are different from those
the elements they contain. Example: salt (sodium
chloride).

Mixtures
• Contain two or more substances combined in such a
way that each substance retains its chemical identity.
 Copper sulfate do not react with sand when it
combine/shake together.
• There are two types of mixtures:
a.a. HomogeneousHomogeneous – or uniform mixtures which the
composition is the same throughout. Also called as
solution (contain solvent and solute).
b.b. HeterogeneousHeterogeneous – or nonuniform mixtures which the
composition varies throughout. Most rocks fall into this
categories.

To learn about matter, you must also familiar with:
• AtomsAtoms - which are composed of electrons, protons
and neutrons.
• MoleculesMolecules - the building blocks of several element and
many compounds. Molecular substances can be
identified by their formulae or their names.
• IonsIons - species of opposite charge found in all ionic
compounds. Using relatively simple principles, it is
possible to derive the formulae and names of ionic
compounds.

Postulates of the Dalton’s Atomic TheoryPostulates of the Dalton’s Atomic Theory
1. All matter consists of atomsatoms.
2. Atoms of one element cannotcannot be converted into atoms
of another element.
3. Atoms of an element are identicalidentical in mass and other
properties and are different from atoms of any other
element.
4.4. CompoundsCompounds result from the chemical combination of a
specific ratio of atoms of different elements.

Some features
of Dalton’s
atomic theory
Some features
of Dalton’s
atomic theory

Structure of the AtomStructure of the Atom
• An atomatom is an electrically neutral, spherical entity
composed of a positively charged central nucleus
surrounded by one or more negatively charged electrons.
• An atomic nucleus consists of protons and neutrons
(except H).
 Proton (p+
) has a positive charge
 Neutron (n0
) has no charge
 Electron (e-
) has a negative charge
• An atom is neutralneutral because the number of protons
in nucleus is equals the number of electrons
surrounding the nucleus.

ElectronsElectrons
• Are common to all atoms, carry a unit negative charge (-
1) and have a very small mass, roughly 1/2000 that of the
lightest atom.
• Every atom contains a definite number of electrons.
 Hydrogen contain 1 electron
 Uranium contain 92 electrons
• Electrons are found in the
outer regions of the atom,
where they form what
amounts to a cloud of
negative charge.

Protons and Neutrons; the atomic nucleusProtons and Neutrons; the atomic nucleus
• Proton, which has a mass nearly equal to that of an
ordinary hydrogen atom.
• The proton carries a unit positive charge (+1), equal in
magnitude to that of the electron (-1).
• The neutron is an uncharges particle with a mass slightly
greater than that of a proton.
• Because proton and neutrons are much heavier than
electrons, most of the mass of an atom (>99.9%) is
concentrated in the nucleus, even though the volume of
the nucleus is much smaller than that of the atom.

Atomic Number, Mass Number and Atomic SymbolAtomic Number, Mass Number and Atomic Symbol
• Atomic number (Z)-Atomic number (Z)- number of protons in nucleus of
each of its atoms.
• Example: C atoms (Z=6) have 6 protons
• Mass number (A)Mass number (A) – the total number of proton and
neutrons in the nucleus of an atom.
• The nuclear mass number and charge are often written
with the atomic symbolatomic symbol.
 Atomic symbol – element symbol based on its English, Latin
or Greek name.
 Atomic number (Z) is written as a left subscript
 Mass number (A) – is written as left superscript

H1
1 Cl
35
17 C
12
6
U235
92 Sr90
38
XA
Z
Mass Number
Atomic Number
Element Symbol
or

Isotopes and Atomic Masses of the ElementsIsotopes and Atomic Masses of the Elements
• IsotopesIsotopes – all atoms of an element are identical in atomic
number but not in mass number (different numbers of
neutrons).
• Example: Carbon (Z=6)Carbon (Z=6) – have 6 protons and 6 neutrons.
 A small % have 7 neutron (A=13) and 8 neutron (A=14).
 Carbon have three isotopes – 1212
C,C, 1313
C andC and 1414
CC
• The chemical properties of an element are primarily
determine by the no of electron.
• So, all isotopes of an element have nearly identical
chemical behavior (even though have different masses).
H
1
1 H
2
1 H
3
1 Cl
35
17 Cl
37
17

6 protons, 8 (14 - 6) neutrons, 6 electrons
6 protons, 5 (11 - 6) neutrons, 6 electrons
How many protons, neutrons, and electrons are in C
14
6 ?
How many protons, neutrons, and electrons are in C
11
6 ?

13 protons, 14 (27 - 13) neutrons, 10 (13 – 3) electrons
16 protons, 16 (32 - 16) neutrons, 18 (16-2) electrons
How many protons, neutrons, and electrons are in Al
27
13
?
3+
How many protons, neutrons, and electrons are in S
32
16
?
2-

Atomic Masses; the Carbon-12 ScaleAtomic Masses; the Carbon-12 Scale
• Individual atoms are far too small to be weighed on a balance.Individual atoms are far too small to be weighed on a balance.
• Atomic massAtomic mass is the mass of an atom in atomic mass units
(amu).
• The atomic mass of an element indicates how heavy, on the
average, one atom of that element is compared with an atom
of another element.
• To set up a scale of atomic mass, it is needed a standard value
for one particular species.
• One atomic mass unitatomic mass unit is defined as a mass exactly equal to
one-twelfth the mass of one carbon-12 atom.

On this scale
1
H = 1.008 amu
16
O = 16.00 amu
1 amu = 1/12 x mass of one C-12 atom
In the periodic table, atomic masses are
listed directly below the symbol of the
element
In the periodic table, atomic masses are
listed directly below the symbol of the
element

Relative Atomic Mass,Relative Atomic Mass, AArr ; Relative Molecule Mass,; Relative Molecule Mass, MMrr
• Some definitions of atomic and molecular masses:Some definitions of atomic and molecular masses:
• If the mass ratio of one atom of an element to one atom ofIf the mass ratio of one atom of an element to one atom of
carbon-12 is known, the relative atomic mass of the element cancarbon-12 is known, the relative atomic mass of the element can
be calculated.be calculated.
Relative atomic mass,Relative atomic mass, AArr of an =of an =
element Xelement X
Mass of one atom of XMass of one atom of X
1/12 x mass of one1/12 x mass of one 1212
C atomC atom
Relative molecular mass,Relative molecular mass, MMrr of a =of a =
compound Wcompound W
Mass of one molecule of WMass of one molecule of W
1/12 x mass of one1/12 x mass of one 1212
C atomC atom

The mass ratio of one atom of nitrogen to one atom of
carbon-12 is 1.24899. What is the relative mass of
nitrogen?
Start from the definition of relative atomic mass of an element
= 12 x 1.24899
= 1.24899Mass of one atom of N
mass of one atom of carbon-12
Relative atomic mass of N = Mass of one atom of N
1/12 x mass of one 12
C atom
= 14.98788

• The amount of each isotope of an element expressed in
percentage is called the relative abundancethe relative abundance or isotopic
abundance of that element.
• The total relative abundance is 100%.
• Element that have more than one isotope – measure the
average mass for all occurring mixture of isotopes.
• If an element has n isotopes, the average atomic mass of the
elements is:
Fraction abundance, f =
Percentage of isotope
100

• Example: Lithium
(7.42 x 6.015) + (92.58 x 7.016)
100
= 6.941 amu

Tentukan jisim atom relatif, Ar bagi unsur Neon yang
diketahui mempunyai tiga isotop iaitu 20
Ne, 21
Ne dan 22
Ne
dengan peratus kelimpahan masing-masing 90. 92%, 0.26%
dan 8.82%.
= 20.18
90.92
100
+Ar Ne = ( )x 20 ( )x 210.26
100
( )x 228.82
100
+

• Relative masses of individual atoms can be determined using a
mass spectrometer.
• The substance to be analysed must first be vapourised to
gaseous atoms or molecules in the vapourisation chambervapourisation chamber.
• The spectrometer is connected to a vacuum pumpvacuum pump so that the
air molecules will not interfere with incoming particles.
• Gaseous atoms or molecules are ionised in the ionisationionisation
chamberchamber as a result of bombardment by the beam of high
energy electrons emitted by an electron gunelectron gun.
 When atom loses electron, positive ion are produced.
 Example: C+
ion is formed when an electron is removed from a
carbon atom.

• In the acceleration chamberacceleration chamber, the cation formed are accelerated
by a potential difference of 500 to 2000V toward a magneticmagnetic
field.field.
• The magnetic field deflects the ions from their straight-line
path (depends on the mass to charge ratio of the ions). The
path of more massive ions curve less than the less massive ions
(species can be separate).
• All ions will be directed to the
detectordetector plate where they
produce a weak signal or current.
• Mass spectrumMass spectrum showing peaks of
various heights at certain
mass/charge (m/e) values.

The mass spectrometerThe mass spectrometer

Mass spectrum of
chlorine
Chlorine contains only two
isotopes: 34.97 amu (75.53%) and
36.97 amu (24.47%)
Average atomic mass ClAverage atomic mass Cl
= (34.97 x 75.53) + (36.97 x 24.47)
100 100
= 35.46 amu

Names and Formulas ofNames and Formulas of Ionic CompoundsIonic Compounds
• Many ionic compound are binary compoundbinary compound or
compound formed from just two element
 Metal (cation)– many metal names end in –ium–ium
 Nonmetal (anion) – adds the suffix –ide–ide in the end of
nonmetal name

• Ternary compoundTernary compound – compounds consisting of three
elements
 Anion groups containing different elements also used ––
ideide
 Example:
 Lithium hydroxide (LiOH)
 Potassium cyanide (KCN)

• Compound with metal that can form more than one ionCompound with metal that can form more than one ion
 Metal in transition element (B groups)
 Example: Iron can form FeFe2+2+
and FeFe3+3+
ion.
 When iron react with chlorine, FeClFeCl22 (iron(II)chloride)
and FeClFeCl33 (iron (III)chloride).
 Common names
 for the ion with the lower charge – ous– ous
 for the ion with the higher charge – ic– ic

• Families of Oxoanions -Families of Oxoanions - Usually nonmetal, is bonded to
one or more oxygen atoms.
 The ion more O atoms takes the nonmetal root, -ate-ate
 The ion fewer O atoms takes the nonmetal root, -ite-ite
ClO4
-
is perchlorate ion
ClO3
-
is chlorate
ClO2
-
is chlorite
ClO-
is hypochlorite
ClO4
-
is perchlorate ion
ClO3
-
is chlorate
ClO2
-
is chlorite
ClO-
is hypochlorite
• If have four oxoanions in the family:

Ammonium NH4
+
Chlorate ClO3
-
Peroxide O2
-2
Acetate CH3COO-
Perchlorate ClO4
-
Chromate CrO4
-2
Nitrate NO3
-
Permanganate MnO4
-
Dichromate Cr2O7
-2
Nitrite NO2
-
Carbonate CO3
-2
Silicate SiO3
-2
Hydroxide OH-
Sulfate SO4
-2
Phosphate PO4
-3
Hypochlorite ClO-
Sulfite SO3
-2
Arsenate AsO4
-3
Chlorite ClO2
-
Thiosulfate S2O3
-2
Arsenite AsO3
-3
Cyanate CN-
Thiocyanate SCN-
Borate BO3
-3
Bicarbonate HCO3
-
Bisulfate HSO4
-
Bisulfite HSO3

• Compound composed of nonmetallic elements.
• Many molecular compound are binary compound.
• Similar to naming binary ionic compounds.
• Adds the suffix –ide–ide in the end of second element.
• Example:
Names and Formulas ofNames and Formulas of Molecular CompoundsMolecular Compounds

HI hydrogen iodide
NF3 nitrogen trifluoride
SO2 sulfur dioxide
N2Cl4 dinitrogen tetrachloride
NO2 nitrogen dioxide
N2O dinitrogen monoxide
TOXIC!
Laughing Gas

• To avoid confusing in naming the
compound, Greek prefixes has been
used to denote the number of atoms
of each element present.
Names and Formulas ofNames and Formulas of Molecular CompoundsMolecular Compounds

• AcidAcid – a substance that yields hydrogen ion (H+
) when
dissolved in water.
• Two common types of acid:
 Binary acidBinary acid solution form when certain gaseous compounds
dissolved in water.
 OxoacidOxoacid – similar to oxoanions except
 Suffix – ate– ate becomes – ic– ic in the acid
 Suffix – ite– ite becomes – ous– ous in the acid
Names and Formulas ofNames and Formulas of Acids and BasesAcids and Bases

Name of
Anion
Name of Acid Examples
.....-ide Hydro.....-ic acid
HCN(aq) cyanide → hydrocyanic acid
HBr(aq) bromide → hydrobromic acid
Per .....-ate Per .....-ic acid HClO4 perchlorate → perchloric acid
.....-ate .....-ic acid
HClO3 chlorate → chloric acid
H2SO4 sulfate → sulfuric acid
.....-ite .....-ous acid
HClO2 chlorite → chlorous acid
H2SO3 sulfite → sulfurous acid
Hypo...-ite Hypo....-ous acid
HClO hypochlorite → hypochlorous
acid

• BaseBase – a substance that yields hydroxide ion (OH-
) when
dissolved in water.
Names and Formulas ofNames and Formulas of Acids and BasesAcids and Bases

• The molemole (mol) is the amount of a substance that contains the
same number of particles (atoms, molecules or ions) that exists
in exactly 12.00 grams of 12
C.
• The definition specifies the number of objects in a fixed mass of
substance.
• A mole represents 6.022 x 1023
particles, whatever they may be.
Therefore, 1 mole of substance = fixed number of chemical
entities and has a fixed mass.

Molar massMolar mass is the mass of 1 mole of in grams
ions
Atoms
Molecules
1 mole 12
C atoms = 6.022 x 1023
atoms = 12.00 g
1 12
C atom = 12.00 amu
1 mole 12
C atoms = 12.00 g 12
C
1 mole lithium atoms = 6.941 g of Li

Mass (g)Mass (g) = no. of moles x no of grams
1 mol
No. of molesNo. of moles = mass (g) x 1 mol
no. of grams
• Convert between amount (mol) and mass (g), use molar
mass ( M in g/mol)
No. of entitiesNo. of entities = no. of moles x 6.022 x 1023
entities
no. of grams
No. of molesNo. of moles = no. of entities x 1 mol
6.022 x 1023
entities
• Convert between amount (mol) and no. of entities, use
Avogadro’s number (6.022 x 1023
entities)
(1)(1)
(2)(2)
(3)(3)
(4)(4)

• Convert between number of entities and mass, first
convert to number of moles.
No. of atomsNo. of atoms = mass (g) x 1 mol x 6.022 x 1023
entities
no. of grams 1 mol
(5)(5)

Berapakah bilangan atom H yang terdapat di dalam 1 mol
gas NH3?
1 mol NH3 mengandungi 3 mol atom H
Bilangan atom H dalam 1 mol NH3
= 3 x 6.023 x 1023
= 1.807 x 1024
atom
Hitung bilangan ion Ca2+
dan ion Cl-
dalam 1 mol CaCl2
1 mol CaCl2 mengandungi 1 mol ion Ca2+
dan 2 mol ion Cl-
= 2 x 6.023 x 1023
= 1.205 x 1024
atom
Bilangan ion Ca2+
=6.023 x 1023
Bilangan ion Cl-

Acetylsalicylic acid, C9H8O4, is the active ingredient of aspirin.
a.What is the mass in grams of 0.509 mol of Acetylsalicylic
acid?
b.How many moles of C9H8O4 are in 1 g sample of aspirin that
contains 91.6% by mass of C9H8O4?
= [9(12.01) + 8(1.008) + 4(16.00)] g/mol = 180.15 g/mol
The molar mass of C9H8O4
a. 0.509 mol x 180.15 g = 91.7g
1 mol
a. 1.000 g x 0.916 x 1 mol = 5.08 x 10-3
mol
180.15 g

The relationships between mass (m in grams) of an element and
number of moles of an element (n) and between number of
moles of an element and number of atoms (N) of an element.
M= molar mass in g/mol
NA = Avogadro’s number

Do You Understand Molar Mass?
How many atoms are in 0.551 g of potassium (K) ?
1 mol K = 39.10 g K
1 mol K = 6.022 x 1023
atoms K
0.551 g K
1 mol K
39.10 g K
x x
6.022 x 1023
atoms K
1 mol K
= 8.49 x 1021
atoms K

Chemistry Lecture Slide Week 1

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