making sense of the periodic table trends and what they mean adapted from:
TRANSCRIPT
Making Sense of the Periodic
TableTrends and what they mean
adapted from: http://www.amnh.org/ology/features/stufftodo_einstein/atommobile_read.php http://www.middleschoolchemistry.com/multimedia/chapter4/lesson2
Watch this video
https://youtu.be/0RRVV4Diomg
Where does the “period” in periodic come from?
Based on where in the periodic table you are, you will see different common properties
Based on where in the periodic table you are, you will see different common properties
We will learn more about the chemical and physical properties of these groups of elements and the molecules they make later in the unit…
for now...back to individual elements.
This is a close up of the first 20 elements
Many common
substances are made
from these 20 elements
To understand how these 20 elements make many different types of substances we must first understand their electrons.
Electrons are the key to making compounds through covalent and ionic bonds (more to come)
Electron “shells”Electrons are in regions around the nucleus that are different distances away from the nucleus
The electrons surround the nucleus in 3 dimensions bu it is easier to show an energy level model in two dimensions like the model that looks like a target.
For example…Take an Oxygen
Atom
This energy level model shows two electrons on the first energy
level and six electrons on the second energy level
Since this atom has a total of eight electrons, it also has eight
protons
the atom with eight protons in its nucleus (atomic number 8) is
oxygen
Here’s how that looks for the first
20 elements
Lewis Dot Structures● Lewis Dot Structures are like simplified electron energy level
model
● The lewis structure contains the element symbol with dots representing electrons
● The only electrons shown are those on the outer energy level, which are known as valence electrons
● The electrons are placed around the element symbol, one at a time, clockwise or counterclockwise, and then grouped in pairs as more electrons are needed
Finding the number of valence electrons going across the
periodic table, each group has one more valence electron
except helium (which only has 2)
The number of valence electrons is incredibly important to bonding