Transcript A. The Chemistry of Life

Let’s Talk Chemistry!
1. The Atom
 basic unit of matter
 made up of protons, neutrons and
electrons
 the atom is neutrally charged (no charge)
Helium Atom: Atomic Number 2
Electron
Proton
Neutron
2. Structure of an atom
The nucleus of an atom:
 Protons are positively charged
 Neutrons have no charge
Electrons:
 in constant motion around nucleus
 negatively charged
Atoms have an equal number of
protons and electrons.
3. Elements
Pure substance
Made of one type of atom
Represented by 1, 2 or 3 letters
4. History of the Periodic Table
Mendeleev designed the first
periodic table
He arranged the elements by
increasing atomic mass
He left blank spaces according to
similarities in columns of elements
More history…
Mendeleev’s blank spaces (or
predictions) were elements that he
claimed were not discovered yet.
As it turns out, he was right!!
Scientists later discovered the
missing elements with the properties
that Mendeleev predicted!
And even more history!
Moseley discovered the atomic
number
He organized the periodic table by
increasing atomic number
This allowed for elements with
similar properties to fall into place
An gave way to the modern periodic
table
5. Molecules
 Smallest unit (part) of a compound
 Hydrogen molecule
Water
6. Compounds
 a substance that contains two or
more different elements
 organic compounds must contain
Carbon
Acetic acid
7. Molecular formula
Shows how many atoms of each
element a molecule contains
Does not tell you about a molecule’s
structure
Examples of molecular formulas
H2O
2 hydrogen
1 oxygen
NH3
1 nitrogen
3 hydrogen
C6H12O6
6 carbon
12 hydrogen
6 oxygen
8. Structural formula
Shows how atoms are arranged in a
molecule
2-dimensional representation of a
molecule’s structure
9. 3-D model
Shows how the atoms are
arranged in a molecule
Is able to be moved or turned,
allowing you to view the molecule
from different angles
3D model