Download SNC1D- Grade 9- Unit: Chemistry March 03,2009 Periodic Table

SNC1D- Grade 9- Unit: Chemistry
March 03,2009
Periodic Table Trends
1.Review:
Ions:
Ions are atoms with either extra electrons or missing electrons.
A normal atom is called a neutral atom. That term describes an atom with a number of
electrons equal to the atomic number.
Isotopes
Atoms of the same element can have different numbers of neutrons.
The different possible versions of each element are called isotopes.
For example, the most common isotope of hydrogen has no neutrons at all.
If you want to refer to a certain isotope, you write it like this: AXZ.
Here X is the chemical symbol for the element
Z is the atomic number
A is the number of neutrons and protons combined, called the mass number.
For instance, ordinary hydrogen is written 1H1.
Other isotopes are 2H1 and 3H1.
2.Today’s Lesson:
Classification of the Elements Worksheet
Mendeleeve, a Russian chemist in the 1870's, was the first to successfully partially
arrange the known elements into a chart that we call today the periodic table.
He arranged the elements according to increasing atomic size. When he did this he
noticed that certain elements grouped themselves into vertical groupings called families
or groups.
The periodic table was later rearranged by Mosely. He arranged the elements by
increasing atomic number. This is the periodic table we are now familiar with.
Elements of the periodic tble are arranged in groups (columns) and periods (rows).
Groups contain elements with similar properties and have the same electron
configuration in their outer shells. These electrons in the outer shell are called valence
electrons.
They determine the properties and chemical reactivity of the element and participate in
chemical bonding. As you go down a group atomic size increases and as you go across
a period, atomic size generally decreases.
PART A
1.Representative Elements (AKA. Main Group Elements)
These consist of all 's' and 'p' block elements excluding the noble gases (group 18
elements).
The chemical properties of the representative elements are determined by the number
of valence electrons in their atoms. The number of valence electrons belonging to the
above two blocks are:
's' block elements: 1 or 2: Same as the group number
'p' block elements: 3 to 8: Group number minus ten
The representative elements are also known as normal or typical elements. Thus on the
basis of their location in the periodic table, these are elements, which belong to groups
1, 2 and 13 to 17.
2. Transition elements
'd' block elements are called transition elements. These elements occupy groups 3 to 12
on the periodic table.
There are four series of transitional elements, '3d', '4d', '5d' and '6d' depending on the
energy levels of 'd' orbitals.
They have a general outermost electronic configuration of (n - 1) d1-10 ns1-2.
The general properties of the transition elements are
1.
2.
3.
4.
They are usually high melting point metals.
They have several oxidation states.
They usually form colored compounds.
They are often paramagnetic.
The transition elements include the important metals iron, copper and silver. Iron and
titanium are the most abundant transition elements. Many catalysts for industrial
reactions involve transition elements.
3. Inner Transition Elements
The 'f' block elements are called inner transition elements. There are two series of 'f'
block elements. These are the '4f' and '5f' series called Lanthanides and Actinides. The
general outer electronic configuration of 'f' block elements is, (n - 2) f1-14 (n - 1) d0-1
ns2.
PART B
Metals
In chemistry, a metal (Greek: Metallo, Μέταλλο) is a chemical element whose atoms
readily lose electrons to form positive ions (cations), and form metallic bonds between
other metal atoms and ionic bonds between nonmetal atoms.
Located on the left side of the table. Each metal is unique, but they share many general
properties.







lustre (shiny surface)
malleable (will bend before breaking)
ductile (may be rolled into wires)
good conductors of heat and electricity
mostly react with acid
mostly solid at room temperature
form ions with a positive charge (tend to lose electrons)
More than 75% of the known elements have the characteristic properties of metals (see
figure below). They have a metallic luster; they are malleable and ductile; and they
conduct heat and electricity.
Nonmetals
Located on the left side of the table.
Like metals, each nonmetal has unique properties, but they also share many general
properties.
There are only 17 nonmetals.






dull (non-shiny surface)
brittle
mostly insulators (poor conductors of heat and electricity)
most do not react with acid
may be solid, liquid, or gas at room temperature
form ions with a negative charge (tend to lose electrons)
Metalloids
Eight other elements (B, Si, Ge, As, Sb, Te, Po, and At) are best described as
semimetals or metalloids.
They often look like metals, but they tend to be brittle, and they are more likely to be
semiconductors than conductors of electricity.
PART C
Alkali metals
Group 1 Elements. These are soft, silvery colored metals.
They are the most reactive group of metals.
They have a single valence electron which they give up easily, forming ions with a 1+
charge.
Hydrogen is generally included in this group, because it has a single valence electron.
However, it does not have any of the other metallic properties, and generally behaves
as a
nonmetal when forming compounds.
Alkaline Earth metals
Group 2 Elements. Shiny, silvery white metals.
They are also highly reactive, but slightly less than the alkali metals.
They have two valence electrons, which they give up to form ions with a 2+ charge.
Halogens
Group 17 Elements. The most highly reactive nonmetals.
All require a single electron to fill their valence shell.
Gaining this electron forms an ion with a 1- charge.
Many periodic tables also list hydrogen with the halogens.
The halogens all form diatomic molecules (molecules formed by two atoms of the same
Element, For example F2)
Noble Gases
Group 18 Elements. All are generally unreactive gases.
They have full valence shells, so they tend to neither gain nor give up electrons.
Also called the inert gases, although they can form compounds under certain
conditions.
Rare earth elements
Lanthanides and Actinides. All are rare metals.
Many lanthanides form alloys (solutions of two or more metals melted together) with
magnetic properties.
All of the Actinides are radioactive.
Separated from the rest of the table so it fits more easily on a standard sized page.