Download Chemistry Periodic Table and Trends Periodic Table The periodic

Chemistry
Periodic Table and Trends
Periodic Table
The periodic table is composed of metals and non-metals. Metals are found on the left of the
staircase, which makes up most of the table, and non-metals are found on the right of the
staircase.
The periodic table is also organized into groups (aka families) and periods of elements.
Periods are rows of elements that go across the periodic table
Groups are columns of elements that go down the periodic table
Elements within groups and families share similar characteristics and properties
For instance, all elements within the same groups
(columns) have the same number of valence
electrons (electrons on the outermost shell of an
atom)
Elements are organized in rows (families) by
increasing atomic number and atomic mass.
Lithium (Li) has an atomic number of 3 and its mass
is 6.941. Beryllium(Be), directly beside Lithium, has
an atomic number of 4, and its mass is 9.012
Atoms of the Periodic Table
All atoms contain 3 subatomic particles: Protons, Neutrons and Electrons
Each have their own charge, and are found somewhere in atoms.
Protons: have a positive charge and are in the nucleus (middle) of an
atom (large mass)
Neutrons: have a neutral charge (or no charge) and are also found in
the nucleus (middle) of an atom (large mass)
Electrons: have a negative charge and circle the nucleus (little mass)
The periodic table contains information about each of the elements as seen in
the Hydrogen diagram to the right.
Atomic Number: each atom has its own atomic number and they
are organized in order on the periodic table
Atomic Symbol: the abbreviated version of the name of the atom
Atom Name: full name of the atom
Atomic Mass: mass of the atom, usually in decimal form
The number of protons, neutrons and electrons can be found for each atom
using the atomic number and atomic mass
*The atomic number of an atom equals the number of protons, and also equals the number of
electrons. Hydrogen has an atomic number of 1, so it has 1 proton and 1 electron.
* The atomic number of an atom (rounded to the nearest whole number) equals the protons plus
the neutrons.
Atomic mass = protons + neutrons or Atomic mass – protons = neutrons
Practice: find the number of protons, neutrons and electrons for each of the atoms below.
P N E
P N E
P N E
P N E
Periodic Trends
With the way that elements are arranged on the periodic table, certain patterns or trends can be
seen as you go from left to right on the periodic table, or from top to bottom. These are known as
periodic trends. They are demonstrated below on the diagram below.
Atomic Radius: Atomic radius is measured from the center of the atom to the outermost orbital
shell of the atom. It increases going down groups of the periodic table because energy shells are
added to accommodate more electrons. For instance, Hydrogen (H), Lithium (Li) and Sodium (Na)
are in the same group (column). For each atom, a new shell is added as you go down the group
because each has more electrons.
Reactivity: Reactivity is how likely atoms will react when coming in contact with other
atoms. Reactivity is different for metals and non metals. The most reactive metals are in the bottom
left corner of the periodic table, and the most reactive non-metals are in the top right corner.
Therefore the trend crosses diagonally across the periodic table.
Electronegativity: Electronegativity is basically how bad atoms want to attract other atoms to
make a bond, so the valence electrons between them in chemical bonds will equal 8. It increases
going across the periodic table because atoms who have only a few valence electrons (left) don’t
want to work that hard to make bonds because they are so far from 8, but the atoms closer to the
right side, whose valence electrons are much closer to 8, REALLY want to make bonds with
other atoms to achieve the octet rule (to fulfill all 8 valence electrons). Those atoms in the last column on
the right are noble gases and already have 8 valence electrons. They don’t make bonds, and
electronegativity does not apply to them.
Ionization energy: Ionization energy is the amount of energy needed to remove a valence electron from
an atom. The amount of energy increases across the periodic table because those elements with more
valence electrons (in the columns farther to the right) want to hang on to them more. Therefore those
atoms with more valence electrons would require more energy to take them away from the atom, than
those with fewer valence electrons.
Boiling Point: The boiling points of atoms increase as the mass of elements increase. So the heavier
elements are, the higher the temperature it takes them to boil.
Practice:
1. Which atom is most reactive? Ca, K, Li, Na
2. Which atom has the most electronegativity? Al, Be, F, N
3. Which atom has the most ionization energy? B, O, P, S
4. Which atom has the biggest atomic radius? Au, Mg, Mn, Sn