Chemistry trends in the periodic table

1. CHEMISTRY TOPIC 3 – TRENDS IN THE PERIODIC TABLE
TRENDS IN THE PERIODIC TABLE
Periods are the row in the periodic table where the elements are arranged. There are 7 such periods in the periodic
table.Allthe elementsin the period have the same number of atomicorbitals.For example,everyelement in the top
row (the 1st period) has one orbital for its electrons. All the elements in the second row (the 2nd period) have two
orbitalsfor their electron.
Group is a column of elements in the periodic table of the chemical elements. For neutral atoms, the number
of valence electrons is equal to the atom's main group number. For example, carbon is in group 4 and has 4
valence electrons.
1. Atomic size is the distance between the center of the nucleus of an atom and its outermost shell. Atomic
size decreases as we move from left to right in a period and it increases when we go down a group.
2. Electronegativity can be understood as a chemical property describing an atom's ability to attract and
bind with electrons. From left to right across a period of elements, electronegativity increases. From top to
bottom down a group, electronegativity decreases. Noble gases, lanthanides, and actinides do not have
electronegativity values. As for the transition metals, although they have electronegativity values, there is
little variance among them across the period and up and down a group.
3. Ionization energy is the energy required to remove an electron from a neutral atom in its gaseous phase.
The ionization energy of the elements within a period generally increases from left to right. This is due to
valence shell stability. The ionization energy of the elements within a group generally decreases from top to
bottom. This is due to electron shielding. The noble gases possess very high ionization energies because of
their full valence shells as indicated in the graph. Note that helium has the highest ionization energy of all
the elements.
4. Electron affinity is the ability of an atom to accept an electron. Electron affinity increases from left to right
within a period. This is caused by the decrease in atomic radius. Electron affinity decreases from top to
bottom within a group. This is caused by the increase in atomic radius.
1. Arrange the following elements according to increasing atomic size. P, Al, Cl, Na, S
2. Arrange the following elements in the increasing order of electronegativity. Be, N, O, C
3. Arrange the following elements according to increasing ionization energy. Ba, Be, Mg, Ca
4. arrange the following elements according to increasing electron affinity. Ne, C, O, Li, N

2. 1. Arrange the following elements according to increasing atomic size. P, Al, Cl, Na, S
2. Arrange the following elements in the increasing order of electronegativity. Be, N, O, C
3. Arrange the following elements according to increasing ionization energy. Ba, Be, Mg, Ca
4. arrange the following elements according to increasing electron affinity. Ne, C, O, Li, N
1. Arrange the following elements according to increasing atomic size. P, Al, Cl, Na, S
2. Arrange the following elements in the increasing order of electronegativity. Be, N, O, C
3. Arrange the following elements according to increasing ionization energy. Ba, Be, Mg, Ca
4. arrange the following elements according to increasing electron affinity. Ne, C, O, Li, N

3. CHEMISTRY TOPIC 3 – TRENDS IN THE PERIODIC TABLE
Periods are the row in the periodic table where the elements are arranged. There are 7 such periods in the periodic
table.Allthe elementsin the period have the same number of atomicorbitals.For example, everyelement in the top
row (the 1st period) has one orbital for its electrons. All the elements in the second row (the 2nd period) have two
orbitalsfor their electron.
Group is a column of elements in the periodic table of the chemical elements. For neutral atoms, the number
of valence electrons is equal to the atom's main group number. For example, carbon is in group 4 and has 4
valence electrons.
1. Atomic size is the distance between the center of the nucleus of an atom and its outermost shell. Atomic
size decreases as we move from left to right in a period and it increases when we go down a group.
2. Electronegativity can be understood as a chemical property describing an atom's ability to attract and
bind with electrons. From left to right across a period of elements, electronegativity increases. From top to
bottom down a group, electronegativity decreases. Noble gases, lanthanides, and actinides do not have
electronegativity values. As for the transition metals, although they have electronegativity values, there is
little variance among them across the period and up and down a group.
3. Ionization energy is the energy required to remove an electron from a neutral atom in its gaseous phase.
The ionization energy of the elements within a period generally increases from left to right. This is due to
valence shell stability. The ionization energy of the elements within a group generally decreases from top to
bottom. This is due to electron shielding. The noble gases possess very high ionization energies because of
their full valence shells as indicated in the graph. Note that helium has the highest ionization energy of all
the elements.
4. Electron affinity is the ability of an atom to accept an electron. Electron affinity increases from left to right
within a period. This is caused by the decrease in atomic radius. Electron affinity decreases from top to
bottom within a group. This is caused by the increase in atomic radius.
CHEMISTRY TOPIC 3 – TRENDS IN PERIODIC TABLE
Periods are the row in the periodic table where the elements are arranged. There are 7 such periods in the periodic
table.Allthe elementsin the period have the same number of atomicorbitals.For example,everyelement in the top
row (the 1st period) has one orbital for its electrons. All the elements in the second row (the 2nd period) have two
orbitalsfor their electron.
Group is a column of elements in the periodic table of the chemical elements. For neutral atoms, the number
of valence electrons is equal to the atom's main group number. For example, carbon is in group 4 and has 4
valence electrons.
1. Atomic size is the distance between the center of the nucleus of an atom and its outermost shell. Atomic
size decreases as we move from left to right in a period and it increases when we go down a group.
2. Electronegativity can be understood as a chemical property describing an atom's ability to attract and
bind with electrons. From left to right across a period of elements, electronegativity increases. From top to
bottom down a group, electronegativity decreases. Noble gases, lanthanides, and actinides do not have
electronegativity values. As for the transition metals, although they have electronegativity values, there is
little variance among them across the period and up and down a group.
3. Ionization energy is the energy required to remove an electron from a neutral atom in its gaseous phase.
The ionization energy of the elements within a period generally increases from left to right. This is due to
valence shell stability. The ionization energy of the elements within a group generally decreases from top to
bottom. This is due to electron shielding. The noble gases possess very high ionization energies because of
their full valence shells as indicated in the graph. Note that helium has the highest ionization energy of all
the elements.
4. Electron affinity is the ability of an atom to accept an electron. Electron affinity increases from left to right
within a period. This is caused by the decrease in atomic radius. Electron affinity decreases from top to
bottom within a group. This is caused by the increase in atomic radius.