the periodic table and the periodic law. development of the modern periodic table there were...
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The Periodic Table and The Periodic Law
Development of the Modern Periodic Table
There were multiple people/scientist who contributed to the making of the periodic table as we know it…..
1. Antoine Lavoiser – compiled a list of the 23 elements known in the late 1790s.
2. John Newland – noticed that if the elements were arranged according to the atomic masses, the properties of the elements were repeated.
He called it the “Law of Octaves”.
Development of the Modern Periodic Table
3. Dimitri Mendeleev – is the person credited with making the 1st periodic table leaving spaces for the predicted elements in future. (It was based on the atomic masses)4. Henry Mosley – he then rearranged the periodic table based on atomic numbers and their characteristics, it is used till this date.
Modern Periodic Table (Recap)
Lavoiser – original 23 elements, 1790’sNewland – Arranged by atomic mass;
Law of Octaves – Properties repeatedMendeleev – Left spaces for future
elementsMoseley – Arranged by atomic numbers
and characteristics (current version)
Break-up of Periodic Table
How is table arranged?What are the rows called?What are the columns called?What are groups?What are families?
Break-up of the Periodic Table
Periods – Rows of the periodic table are called the periods. (7 periods at present)
Periodic Table
two rows below the periodic table are the lanthanide and actinide series
these rows fit after #57 and #89
they are only at the bottom to keep the width of the chart smaller
Break-up of Periodic Table
Period
Break-up of the Periodic Table
Groups/Family – Columns in the periodic table are called the groups. There a total of 18 but further classified:All “A” groups – representative elementsAll “B” groups – transition element
Groups have similar properties
Break-up of Periodic Table
Break-up of the Periodic Table
Within the groups and periods there is further classification:Metals
Non-metals
Metaloids
Break-up of the Periodic Table
Within the groups and periods there is further classification:Metals – located on the left, center and
bottom of the periodic table.
Break-up of Periodic Table
Break-up of the Periodic Table
Metals Usually, solids at room temperature. Solid at room temperature (all but Hg) malleable- can be rolled or hammered into sheets ductile- can be made into wire high tensile strength- can resist breakage when
pulled Lustrous – shiny most have silvery or grayish white
luster
Break-up of the Periodic Table
Within the groups and periods there is further classification:Metals – located on the left, center and
bottom of the periodic table. Non-metals – They are located on the right
side of the table.
Break-up of Periodic Table
Break-up of the Periodic Table
Non-metalsMany are gases If in solid form, they are brittle They are poor conductors of heat and electricity
Break-up of the Periodic Table
Within the groups and periods there is further classification:Metals – located on the left, center and
bottom of the periodic table. Non-metals – located on the right side of the
table.Metalloids – located on the “staircase” seen
in the periodic table.
Break-up of Periodic Table
Break-up of the Periodic Table
MetaloidsAlso, known as “semi-conductors” They exhibit properties of both metals and non-
metals.B, Si, Ge, As, Sb, Teall are solids at room temperature less malleable than metals but less brittle than
nonmetals
The s, p, d and f blocks
s-block elements – Groups 1 and 2 (1-A and 2-A)Group 1 (1-A) – are called Alkali metalsGroup 2 (2 – A) – are called Alkaline earth
metalsp-block elements – Groups 13 – 18 (3-A
=> 8-A)Group 17 (7-A) – are called HalogensGroup 18 (8-A) – are called Noble gases
The s, p, d and f blocks
d-block elements – are the B group elements (Groups 3 – 12 or 1B – 8B)They are called transition metals
f-block elements – are also within the B group placed at the bottom of the periodic table.They are known as the inner-transition
metalsThey are also classified as the Lanthanide
and Actinide series
Periodic Trends
What is an ion?An ion is a charged atom or molecule. It is charged because the number of
electrons do not equal the number of protons in the atom or molecule.
An atom can be positively charged or a negatively charged depending if the number of electrons in an atom is greater or less then the number of protons in the atom.
Ions
Periodic Trends
Periodic Trends
What is a trend?It is a characteristic that is repeated. (OR
the general course or prevailing tendency)
In the periodic table trends occur across a period and down the group. For example: The elements get less metallic across the period The elements become larger in size down a group.
Periodic Trends
Atomic Radius: It is the distance from the center of the nucleus to the outermost energy level where there are electrons.
It increases down the group. Why?The principal energy level increases.
It decreases across the period. Why?The energy level is the same but the
number of electrons increases and hence the electrostatic attraction increases.
Pg. 163
Periodic Trends
Ionic Radius: It is the distance from the center of the nucleus to the outermost energy level where there are electrons in an ion.
Positive ions are smallNegative ions are largePg. 166
Periodic Trends
Ionization Energy (I.E.): It is the amount of energy needed to remove an electron from an atom. (pg. 167 – 168)The amount of I.E. increases across a
period (that is left to right) WHY?The more electrons in the outermost orbital
hence more electrostatic attractionThe amount of I.E. decreases down a group
WHY?The electrons are further away form the nucleus
Periodic Trends
Electronegativity (E.N.): It is known as the ability of an atom to attract electrons. (pg. 169)E.N. increases across a periodE.N. decreases down a group
Noble gases are ignored.Fluorine has the largest E.N.Francium the smallest E.N.
Practice Problems
Which has a higher ionization energy?
1. Fe or Cu
2. Na or Rb
3. Ge or Ga
4. C or Si
Practice Problems
Which is bigger?
1. K or Li
2. B or Al
3. O or F
4. Fe2+ or Fe+
Practice Problems
Which has a greater electronegativity?
1. Ca or Sr
2. Cu or Ag
3. Al or Cl
4. F or N
Choose the element with the smaller radius
1. Chromium or tungsten
2. Cadmium or silver
3. Tin or antimony
Choose the element with the larger ionization energy
1. Magnesium or aluminum
2. Lithium or potassium
3. Yttrium or scandium
4. Carbon or germanium
Choose the element with the smaller electronegativity
1. Lead or Bismuth
2. Bromine or astatine
3. Gallium or phosphorus
4. Mercury or Gold
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