Download The Atom

The Atom
Atomic Structure
Nucleus
Electron Cloud
Nucleus
Core of Atom
Contains most of mass of atom
1 amu (atomic mass unit)
6 x 10 23 protons equal one gram
Contains
Proton
Positive charge
1 amu
Neutron
No charge
1amu
Electron Cloud
Surrounds the small nucleus
Contains mostly empty space
Largest part of atom
Contains very little (considered no) mass
Electron Cloud & Energy Levels
Energy levels
Areas where electrons travel
Closest to nucleus- least energy
Electrons move between energy levels
Electrons
In electron cloud
Have negative charge
Have almost no mass- takes 1836 to equal 1 proton’s mass
Number of protons and electrons are the same in an atom
Electrons determine an elements chemical properties
Atomic Number
The number of protons in nucleus of atom
The number of protons in the nucleus determines what element
is
Atomic number of an element never changes
Atomic Mass
The number of protons plus the number of neutrons in an atom
Mass is an average of isotopes of an atom
Element Key
Isotopes
Number of neutrons in atom can vary
Number of protons is constant
Carbon6 Protons
4, 6, 7, 8 neutrons
Mass can vary from 10 to 14
Average is mass of 12- all others are isotopes
Can get mass with decimal – but can’t get a partial
proton or neutron!
Sample Problems
An elements has 35 protons and 47 neutrons; a second
element has 34 protons and 47 neutrons. Are they isotopes or
different elements?
Different number of protons- different elements
Sample Problems
Element x has an atomic number of 40 and has 42 neutrons;
Element y has 40 protons and 40 neutrons. Are they the
isotopes or different elements?
Same number of protons- Isotopes
Bohr’s Diagrams
Include nucleus with number of p and n
Include electron cloud number of energy levels
Shows number of electrons per energy level.
Include examples in notes!