atomic structure and the periodic table - coach cowan: 7th … · 2019-09-02 · atomic structure...
TRANSCRIPT
Atomic Structure and the
Periodic Table
Atomic Structure
Atoms are made of three particles:
1. Protons = positive
2. Neutrons = neutral
3. Electrons = negative
The protons and neutrons are in the center of
the atom (the nucleus)
Electrons buzz around in a cloud around
the nucleus
Atomic Structure
Periodic Table
Different kinds of atoms make different elements
Elements are organized in the Periodic Table
Printed on a Periodic Table are several important
pieces of information
Periodic Table
Periodic Table
A lot of thought went into how the Periodic Table is
organized
● They are arranged in order of number of
electrons
● Columns (groups) have similar chemical and
physical properties○ Also have same number of valence electrons
● Rows (periods) have the same number of
electron layers
● Elements are also arranged by how metallic
they are○ Metals to the left, non-metals to the right
Periodic Table
Metalloids
Periodic Table
Periodic Table
Atomic
Symbol
Atomic
Number
Protons Neutrons Electrons Atomic Mass
B 5 5 6 5 11
Look at the example below which is completed for the element Boron. For the following, complete the table following this example.
Periodic Table
Atomic
Symbol
Atomic
Number
Protons Neutrons Electrons Atomic Mass
11 24
Complete the missing parts of the table below using the Periodic Table to identify the element symbol and the number of subatomic particles for that element.
Periodic Table
Atomic
Symbol
Atomic
Number
Protons Neutrons Electrons Atomic Mass
31 37
Complete the missing parts of the table below using the Periodic Table to identify the element symbol and the number of subatomic particles for that element.
Atomic Structure
Let’s break that down a bit….
● The classic model of an atom (the Bohr model) has protons and neutrons in
the middle, surrounded by circling electrons
Atomic Structure
● In the Bohr model, electrons stay in rings called “orbitals”
● Each shell (layer of ring outside the nucleus) can only have a certain number of electrons
Atomic Structure
Shells on the Periodic Table. Each ‘shell’ is one full ring around the nucleus. Each
additional shell is a full circle around the outside of the first. The number of shells
depends on the ‘period’ (horizontal row) the element is in on the Periodic Table. Look at
the pictures below. Can you identify how many shells an element in the 4th period down
(light blue) would have?
Atomic Structure
● The outermost shell (ring/orbital) contains special
electrons called valence electrons
● These electrons are very important because they
determine how reactive the atom is (how likely it is to
bond or join with another atom)
○ A full shell means the atom cannot react with another atom
○ Having 8 electrons = a full shell
○ Atoms want to have as many electrons in the outer shell as possible
because they want to be “stable”
Atomic Structure
Valence electrons (electrons in the outer shell) can be identified by the
column number on the Periodic Table, as seen below. Elements in the first
vertical column have ONE valence electron (we do not look at the middle
chunk of elements for this trend).