Download Chemical Periodicity

Kelly Yeung
Chemistry 11
November 10, 2016
Chemical Periodicity
References:
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CK-12.org – Periodic Table
Crash Course Chemistry – The Periodic Table
This unit begins by reviewing concepts covered in grades nine and ten science.
1. List the properties of:
a) metals: relatively unreactive, shiny, good conductors of electricity and heat and, solid at room
temperature (except for mercury), broad variety of melting points, malleable, ductile, similar to
each other, 80% of elements are metals.
b) Non-metals: opposite properties of metals, poor conductor of electricity and heat, exist in all
three states of matter, the majority are gases, the solids are brittle and not lustrous, and melting
points are lower than metals, broad variety of uses, gain electrons easily.
c) metalloids or semimetals: possesses characteristics of metal and non-metals, also have a
variety of uses.
2. Who is Dmitri Mendeleev, and what was his contribution to chemistry?
Dmitri Mendeleev was a Russian chemist and teacher who published the first periodic table of elements.
3. How is the modern periodic table different from the first periodic table?
Mendeleev’s periodic table was organized by atomic mass instead of increasing atomic number.
4. What is the modern periodic law?
The modern periodic law is when elements are arranged in order of increasing atomic number (number
of protons in the nucleus), there is a periodic repetition of their chemical and physical properties.
Todays periodic table uses the modern periodic law.
5. Organization of the periodic table. Indicate where the following are located on the periodic table.
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)
m)
n)
periods: each horizontal row corresponds to the beginning of a new period (seven).
groups: the vertical columns of elements which similar chemical properties
Alkali metals: far left column
Alkaline Earth Metals: second column from the left
Halogens: second column from the right
Noble Gases: far right column
Representative or Main Group elements: the first two columns on the far left and the metals,
metalloids, and non-metals in the six columns on the far right (separated by the bridge of
transition metals)
Transition Metals: middle rectangular block
Inner Transition Metals: the island of two rows below all the other elements
Lanthanides: top row of the island outside the table in the inner transition metals.
Actinides: bottom row of the island outside the table in the inner transition metals.
Metals: all the elements to the left of the diagonal line of metalloids on the right of the table.
Non-metals: top right section of elements
metalloids: shaded diagonal line on the right side of the table.
Kelly Yeung
Chemistry 11
November 10, 2016
6. Indicate which elements on the periodic table are:
a) gases at room temperature: Hydrogen, helium, nitrogen, oxygen, fluorine, neon, chlorine,
argon, krypton, xenon, and radon.
b) liquids at room temperature: Bromine and mercury.
7. Trends in the periodic table.
a) How does the size of the atom vary as you move left to right across the periodic table? Why?
The atomic radius of atoms typically decreases from left to right across a period. This is because
the force of attraction between nuclei and electrons lessens as you move down the table due to
the electron-electron repulsions that would otherwise cause the atom’s size to increase.
b) How does the size of the atom vary as you move down the periodic table? Why?
The atomic radius of atoms generally increases from top to bottom within a group. As the
atomic number increases down a group, there is an increase in the number of occupied principle
energy levels which consist of orbitals that are larger than orbitals from lower energy levels.
c) What is ionization energy?
Ionization energy is the energy required to remove an electron from a specific atom. It is
measured in kJ/mol, which is an energy unit.
d) How does the ionization energy vary as you move left to right across the periodic table? Why?
The ionization energy for an atom increases moving left to right across the periodic table. This is
because the more protons in the nucleus, the stronger the attraction of the nucleus it electrons
there is, making it more difficult to remove electrons.
e) How does the ionization energy vary as you move down the periodic table? Why?
Ionization energy decreases as you go down the periodic table because the atomic radius
increases. The further away an electron is from the positive attraction of the nucleus, the easier
it is for that electron to be pulled off.
f) What is electron affinity?
Electron affinity is the energy change that occurs when a neutral atom gains an electron.
Electron affinities are measured on atoms in the gaseous state and are very difficult to measure
accurately.
g) How does electron affinity vary as you move left to right across the periodic table? Why?
In general, electron affinities increase (become more negative) from left to right across a period.
However, there are many exceptions since it is difficult to accurately measure electron affinities.
h) How does electron affinity vary as you move down the periodic table? Why?
In general, electron affinities decrease (become less negative) from top to bottom down a
group. However, there are many exceptions since it is difficult to accurately measure electron
affinities.
i) What is electronegativity?
Electronegativity is a measure of the ability of an atom to attract the electrons when the atoms
is part of a compound. It is not measured in energy units, but is rather a relative scale with all
elements compared to one another with the most electronegative element, fluorine.
j) How does electronegativity vary as you move left to right across the periodic table?
Electronegativities generally increase from left to right across a period due to an increase in
nuclear charge. Since most noble gases do not form compounds, they do not have
electronegativities.
k) How does electronegativity vary as you move down the periodic table?
Electronegativities generally decreases from top to bottom within a group due to the larger
atomic size.