John Dalton:
- Responsible for atomic theory.
- Atoms small spherical “building
blocks” of everything in the
world.
- Thought atoms were indivisible
and indestructible.
- Is this true?
Also credited with creating the
“disappointed teacher” face.
John Dalton:
Right: Atoms of one kind are called
“elements”.
Combinations of different kinds of
“atoms” are called compounds.
Wrong:
Atoms are not the smallest “simplest” building
block to exist. Atoms are themselves made up
of subatomic particles.
What are these called?
Compounds exist in fixed ratios of
atoms for example: NaOH will
always being NaOH even if there
are millions of molecules of NaOH
in one spot the compound will
always be made up of 1 Na, 1 O
and 1 H.
John Dalton:
Right:
Also said that non-metallic elements, such as sulfur exist in set numbers (natural form).
Sulfur in nature exists as S8 in a octagon shape. This is true for many non-metallic
substances. Other examples?
Several non-metallic elements are monatomic. This means they exist as individual atoms,
known as the noble gases they are inert (do not react).
Are made up of usually 1-2 letters (with a few exceptions we will probably never
use).
How you write element symbols IS important.
CO is not the same as Co.
Homework:
1.2 review.
Determines mass
Homework:
1.3 review.
Student book:
WS: 2
What defines an atom?
What makes carbon,
carbon?
What makes Hydrogen,
hydrogen?
A
Mass number
Z
Atomic
number
protons
Protons and neutrons
Mass number
Z
A
Atomic
number
Looking at both representations:
How can we always tell which is the atomic
number and which is the mass number?
Charge must balance to be stable. Therefore
the numbers of protons must be equal to
the number of………?
All atoms that belong to the same element WILL have the same
number of protons.
However, some atoms can have differing numbers of neutrons.
What aspect of the atom does this change?
The weight?
The mass?
The shape?
The reactivity?
Homework:
1.4 review.
Work sheet 2
(SB)
Homework 1.5
review.