Download Year 11 Chemistry: Chapter 3 ~ The Periodic Table

Year 11 Chemistry: Chapter 3 ~ The Periodic Table
3.1 Why is that Periodic Table important?
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Mendeleev’s periodic table was an inspired development. Not only did it organise the
information gathered on the basis of patterns of chemical properties and behaviour,
but it also proved to be a useful tool for predicting and guiding future developments
in Chemistry.
Knowing the properties of particular elements and trends within the table, chemists
can comprehend what would otherwise be an overwhelming collection of disorganised
experimental observations.
3.2 Why are Element Properties Periodic?
Mendeleev proposed his periodic law: The properties of elements vary periodically
with their atomic weights.
To understand the reason for the periodicity of element properties, lets have a look
at the alkali metals (group ) and the halogens (group ). Group 1 (I) _______ metals
are all relatively soft and highly reactive with water and oxygen. List the group 1
metals and their electronic configurations (subshell):
Element Name
Element Symbol Electronic Configuration
Lithium
Sodium
Potassium
Rubidium
Cesium
* They all have one electron in an s-subshell.
Group 17 (VII) ________ are all coloured and are also highly reactive, especially
Fluorine and Chlorine. List the Group 17 halogens and their electronic configuration
(subshell):
Element Name
Element Symbol Electronic Configuration
Fluorine
Chlorine
Bromine
Iodine
* They all have the configuration s2p5 as the outer shell.
The electrons in the outer shell of an atom are known as the valence electrons.
The arrangement of electrons in atoms is responsible for the periodicity of
element properties.
List some properties that the outer-shell electrons in an atom are responsible for:
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Variations of the chemical properties of elements across a period and
similarities down a group are all associated with the electronic configurations
of their atoms.
Patterns in Electronic Structure
 Vertical columns are called __________ , and elements have similar outershell electronic configurations.
 Horizontal rows are called _______ . The number of the period is the same as
the number of the outer-shell.
Blocks of Elements
There are four main blocks in the periodic table:
 __________ contains Group 1 (alkali metals) and Group 2 (alkaline earth
metals): half fill or fill ________ .
 _________ contains elements in Groups 13-18 (III – VIII): ________
These are the two main blocks.
Exceptions:
Hydrogen: _______________________________________________________
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Helium: __________________________________________________________
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 _________ contains the transitional metals. The d-subshells are filled only
after the s-subshell of the next shell has been filled: __________________
 _________ contains the lanthanides (___ ) and actinides (___ ).
Uranium is the last element to been found naturally occurring on Earth. The
transuranic (atomic numbers higher than 93) elements have been created in a
laboratory.
QUESTIONS: 1c, 2, 3, 4, 5, 6, 7 & 17.
3.3 Trends in Properties
Atomic Properties
The properties of radius, ionisation energy and electronegativity all depend on the
strength of the attraction between the __________________ and the _________.
Define ‘electronegativity: ___________________________________________
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This attraction will depend on:
 the ___________ charge that attracts the outer-shell electrons.
 The distance of the ___________ from the nucleus.
*Annotate the diagrams below:
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Core Charges
*Draw: fig3.9
 Moving down a group, the core charge remains __________ but the number of
electron shells ____________. The outer-shell electrons are therefore held
less strongly.
 The electrons in atoms of elements in the same period are located in the same
outer shell. Moving across a period, as the core charge ____________ the
outer-shell electrons are pulled more and more _________ towards the atom’s
nucleus.
Metallic and non-metallic Character
Elements on the right side of the table are ___________ . Other elements are
___________. As you move left to right the elements become _______ metallic and
exhibit more ___________ properties.
There is no variation in metallic character within ________.
Metalloids: _______________________________________________________
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Germanium, silicon, arsenic and tellurium.
Chemical reactivity of the elements
Reactivity of Metals:~
*Look at Table 3.2 and the periodic table: Discuss
 Metals in group 1 are ________ reactive than those in group 2.
 Down a group, the reactivity of the metal in water ___________ .
This trend in reactivity can be explained in terms of the changes in atomic size and
ionisation energy.
When metals react they tend to form _________ions (_________) ~ by donating
one or more of its valency electrons to other ________. The metal atom with the
_________ first ionisation energy will require the least energy to donate electrons
~ therefore tend to be the ________ reactive.
Reactivity of Non-metals
The halogens are in a similar boat to the group 1 metals. The reactivity of halogens
decrease from period 2 to 5. This can be explained in terms of the changes in atom
size and electronegativity.
The Noble Gases
The elements in Group 18 (group VIII) are called ____________.
 They are all very ___________ gases.
 They all have very _______ melting and ________ temperatures
 All are ______ at room temperature.
HELIUM BOILS AT -269°C , 4°C ABOVE ABSOUTE ZERO
The lack of reactivity of these elements arises from the arrangement of electrons in
their atoms.
Element Name
Symbol
Electronic configuration
Helium
Neon
Argon
Krypton
Nobel gases have been known to form compounds with fluoride ions.
QUESTIONS:
3.4 Compounds
Compounds are formed when atoms of two or more elements chemical combine in
fixed proportions. Each compound has its own characteristic set of properties, which
are quite different from those of the elements it contains.
Example: Sodium Chloride ( ____ ) ~ common salt, always contains 39.3% Sodium and
60.7% of Chlorine, by mass, no matter is our sample is 1g, 2g, 5g or even 10kg.
The properties tell us something about the particles present and the strength of the
forces between the particles. A large number of compounds that are metal and nonmetal combined ( _______ compound) have similar characteristics of sodium chloride.
Sodium
Metal
Chlorine
Non-metal
Sodium Chloride
Ionic compound
Summarise properties of the compound __________________________________
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Molecule: is two or more non-metal atoms chemically combined. Example H2O.
*Can you think of any others? _________________________________________
They have similar properties
Hydrogen
Oxygen
Water
Non-metal
Non-metal
Covalent molecule
Summarise properties of the compound __________________________________
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QUESTIONS: 11, 12, 13, 14, 26, 27 & 29.
KEY TERMS & CHAPTER OUTCOMES (don’t worry about: actinides & lanthanides)
Chapter 4 ~ Relative Atomic Mass and Mole
* There will be a test after this chapter.
4.1 Masses of particles
Relative Isotopic mass
Dalton estimated relative atomic weights based on a value of one unit for the
hydrogen atom. In 1961 it was decided that by the International Union of Pyysics and
Chemistry that the most common isotope of carbon, 12C, would be used as the
reference standard, therefore given the relative mass of exactly 12 units.
The relative isotopic mass (___) of an isotope is the mass of an atom of that
isotope relative to the mass of an atom of 12C as 12 units exactly.
Chlorine: There are two different atoms ( __________ ) of the element chlorine.
Compared to carbon-12 their weights are 34.969 (35Cl) and 36.966 (37Cl). Naturally
occurring chlorine is made up of 75.80% of the lighter isotope and 24.20% (relative
abundance) of the heavier isotope. This composition is virtually the same no matter
the source.
Relative isotopic masses of elements can be obtained using an instrument called the
____________________. It produces a graph called __________________ .
Mass Spectrum
 The number of peaks = number of
__________ .
 Position of each peak on the
horizontal axis designates relative
isotopic mass.
 The relative heights of the peaks
corresponds to the relative
abundance of the isotope.
EXTENSION: E1a&b
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Relative Atomic Mass
A naturally occurring sample of an element contains the same isotopes in the
same proportions, regardless of its source. An average weight of the atom can be
calculated using the relative isotopic masses with their abundances known as ______
_____________ and is given the symbol _______ .
*The relative atomic mass of an element is, therefore, the weighted average of the
relative masses of the isotopes of the element on the 12C scale.
Example: Imagine taking 100 atoms from a sample of chlorine – there will be 75.80
atoms of 35Cl and 24.20 atoms of 37Cl.
Therefore relative atomic mass of 100 atoms =
The average relative mass of one chlorine atom =
(relative isotopic mass X abundance) + (relative isotopic mass X abundance) + …..
100
Therefore:
The relative atomic mass of chlorine is _______
Or more simply Ar(Cl) = ______
What do you notice:
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Example: Boron has two isotopes. Calculate the Relative Atomic mass. Show all steps.
Isotope
10
B
11
B
Relative Abundance (%)
19.91
80.09
Relative isotopic mass
10.013
11.009
Example: Copper has two isotopes. 63Cu has a relative isotopic mass of 62.95 and
65
Cu has a relative isotopic mass of 64.95. The relative atomic mass of copper is
63.54. Calculate the percentage abundance of the two isotopes.
*HINT: Let x be the % abundance of 63Cu, So (100-x) must be % abundance of 65Cu.
Relative Molecular Mass
The relative molecular mass ( ____ ) of a compound is the mass of one molecule of
that substance relative to the mass of a 12C atom, which is ____ exactly.
Example: Relative molecular mass of atmospheric oxygen (O2).
Oxygen (O2): Mr(O2)
= 2 x Ar(O)
= 2 x 16.0
= 32.0
Relative molecular mass of atmospheric carbon dioxide (CO2).
*For non-molecular compounds (ionic etc), the term relative __________ mass is
used.
Example: Find the relative formula mass of Sodium chloride (NaCl).
QUESTIONS: E1, 1, 2, 3, 4, 19, 21, 22 & 24.