Upload
august-maxwell
View
218
Download
0
Embed Size (px)
DESCRIPTION
Most elements with atomic numbers less than 93 are natural - the exist naturally on Earth The other elements are synthetic (man-made) Once the relationships between elements were established, scientists could predict other elements that could be made Based on what the atomic structure should be (according to position on periodic table)
Citation preview
The Periodic Table So you thought you knew ...
Mendeleev’s Arrangement
By mid-1800’s, chemists needed a way to organize the 50+ elements already discovered
Russian chemist, Dimitri Mendeleev found a pattern when he placed the elements in order of increasing atomic mass
The properties of the elements appeared in regular intervals, or periodically - hence, the Periodic Table
The Modern Periodic Table Most elements with atomic numbers less than
93 are natural - the exist naturally on Earth
The other elements are synthetic(man-made)
Once the relationships between elements were established, scientists could predict other elements that could be made Based on what the atomic structure should be
(according to position on periodic table)
Classes of Elements
We can predict the physical and chemical properties of an element based on its position in the table
3 classes: Metal Non-metal Metalloid
Copy the following table into your notes:
Classes of Elements cont’d
MATERIAL
STATE AT ROOM TEMP.
APPEARANCE
CONDUCTIVITY(Heat & Electricity)
MALLEABILITY & DUCTILITY
Metals
Non-Metals
Metalloids
Classes of Elements cont’d
MATERIAL
STATE AT ROOM TEMP.
APPEARANCE
CONDUCTIVITY
MALLEABILITY & DUCTILITY
Metals Solid (except mercury – liquid)
Shiny Good Malleable Ductile
Non-Metals
Some gas, some solid (except Bromine – liquid)
Not very shiny
Poor Brittle Not ductile
Metalloids
Solids Can be shiny or dull
May conduct electricity,Poor conductor of heat
Brittle Not ductile
Where are they on the PT?
Metals
Non-Metals
Metalloids
In-Class Assignment: Read pages 202 – 204: Mining For Metals; Metals
and Health; Diamond Mining. Answer the following questions:
1. What compound is used to extract gold from ore?2. What are the negative effects of gold mining and
refining?3. How is iron used in your body?4. What organs can be injured if iron levels in the body
are too high?5. Name the two processes that result in high
concentrations of metals in animals.6. Why are waterways a key source of mercury
poisoning? 7. Answer question 1 on p. 203.8. In point form, describe four ways diamond mine
companies contribute to their local communities. Do you think mine companies did this around 100 years ago?
What Else Can the Periodic Table Tell Us?
Elements are organized into periods and groups
Periods are horizontal rows, numbered 1 to 7, starting from the top
Rows and rows... Even though they skip some squares in between,
all of the rows go from left to right
Elements in the same row have something in common - the same number of energy levels (or electron shells)
Every element in the top row (the first period) has one electron shell for its electrons
All of the elements in the second row (the second period) have two electron shells for their electrons, etc
At this time, the maximum number of energy levels or electron shells for any element is seven
Groups
Groups (or families) are vertical columns
They are numbered 1-18, starting on the left
Groups When a column goes from top to bottom, it's
called a group. The elements in a group have the same
number of electrons in their outer energy shell
Every element in the first column (group one) has one electron in its outer shell.
Every element on the second column (group two) has two electrons in the outer shell... etc
N.B. There are exceptions to the order when you look at the transition elements, but you get the idea.
For now, “1,2, skip a few, minus 10”
Happy Atoms Electrons want to be happy
They are happiest when their outermost energy level is full of electrons!
During a chemical reaction, one atom can join with another atom by gaining, losing, or sharing valence electrons
Valence electrons determine how reactive an element is
All in the Family (Anybody? Anybody?)
Families are groups of elements with similar chemical properties
Each family reacts and behaves differently
4 important families are1. Alkali Metals2. Alkaline Earth Metals3. Halogen Gases4. Noble Gases
Alkali Metals (Group 1)
Traits: Very reactive – why? They all have 1 electron
in their outer shell. That’s 1 away from being happy (full shell)
Increased desire to bond (and lose electron) = more reactive
Alkali Metals cont’d
MORE TRAITS:
Low melting points
Shiny
Light in weight
Soft
EG. SODIUM
Alkaline Earth Metals – Group 2
2nd most reactive family Needs to get rid of 2
valence electrons to be happy
When heated, they will burn in air and produce bright, colourful flames Eg. Magnesium Often used in fireworks
Very important in physiology Eg. calcium
Eg. Magnesium
Halogens – Group 17
How many valence electrons ? 7 – only 1 short of being full
Because they are so close to being happy, they combine with many different elements Very reactive non-metals! Often bond with elements from Group 1
Halides Extremely corrosive
Chlorine and Iodine are both used as disinfectants
When a halogen combines with another element, the compound is called a halide Sodium Chloride (NaCl) is a
halide
Inert Gases - Group 18
Aka Noble gasesAka group zeroHappiest elements of all!
Outer electron shells are fullHappy not reacting with other
elements – rarely combine Non-reactivity = inert
Odourless, colourless gases (at room temp.)
When they do bond, they were forced
Outlaws:
HYDROGEN
Has talents of 2 groups: one and seven
either missing an electron or have one extra
NOT an alkali metal It’s a gas
HELIUM
Even though it only has 2 valence electrons, it is still in the inert gas family
There’s one in every family, right?
Transition Metal Groups
Transition metals (groups 3-12) are special They have a lot of electrons that are
distributed in different ways (i.e. They don’t follow the pattern)
Can use the two outermost shells to bond with other elements (instead of just outermost) Most have two shells that aren’t “happy”
The last two...LANTHANIDE SERIES Aka: Rare-earth
metals or inner transition metals
Found naturally on earth Except for Promethium
(Pm) - radioactive
ACTINIDE SERIES All radioactive
elements Some with higher
atomic numbers have only been made in labs Particle accelerators