Download Script of atoms video

We are made up of elements
Properties determined by the atoms that make them up
Each atom made up of three particles
Protons (mass=1; charge=+1)
Neutrons (mass=1; no charge)
Electrons (mass =0; charge=-1)
Protons & neutrons are in the nucleus
A helium atom
(fig. 2.3)
(fig. 2.3)
# of protons gives identity of the element (atomic number)
So what is helium’s atomic number?
(fig. 2.3)
Protons + Neutrons gives atomic mass
So what is the atomic mass of helium?
(fig. 2.3)
For uncharged (electrically neutral) atoms:
# of protons = # of electrons
Re-cap
Protons and neutrons are in the nucleus
Their combined mass gives the mass of the atom
Electrons “orbit” the nucleus
Organized in energy shells
Electron shells
figure 2.5
e- are negatively charged
-> attracted to nucleus
Takes E to “push” them to higher shells
Release E when they “fall” back down
Shells fill from lowest to highest
Electron shells
figure 2.6
1st shell
Holds 2 end
2 shell
Holds 8
rd
3 shell
Holds 8
Valence shell
Outermost shell with e- present
Electron shells
figure 2.6
Look at carbon
How many e- in its valence shell?
How many more would it take to fill?
(pause the video if necessary)
Electron shells
figure 2.6
Look at oxygen
How many e- in its valence shell?
How many more would it take to fill?
(pause the video if necessary)
Electron shells
figure 2.6
Look at neon
How many e- in its valence shell?
How many more would it take to fill?
(pause the video if necessary)
Electron shells
figure 2.6
Difference b/w neon and other atoms shown?
Valence shell
Full
Not full
If not full
Atoms will react to fill
Form bonds
Next lecture ;)