1. I. Structure of the Atom Chemical Symbols Subatomic Particles
Ch. 2 – Basic Chemistry
I. Structure of the Atom
Chemical Symbols
Subatomic Particles

2. Metal that forms bright blue solid compounds.
Chemical Symbols
Chemical Symbols are used to represent element names
Capitals matter!
Element symbols contain ONE capital letter followed by lowercase letter(s) if necessary.
Must be written correctly or will be wrong on quiz/test
Metal that forms bright blue solid compounds.
Co vs. CO
Poisonous gas.

3. What elements must you know…
You must memorize elements 1-20 on the periodic table
H = hydrogen
He = Helium
Li = Lithium
Be = Berrylium
B = Boron
C = carbon
N = nitrogen
O = oxygen
F = fluorine
Ne = Neon
Na = sodium

4. Continued Mg = magnesium Al = aluminum Si = silicon P = phoshorus
S = sulfur
Cl = chlorine
Ar = argon
K = potassium
Ca = calcium

5. What other elements must I know
You must also memorize the elements on the memorization tips sheet you got
Quiz on _________ at the beginning of the hour
Ag = silver
Au = gold
Br = Bromine
Fe = iron
Hg = mercury
Ni = nickel
Pb = lead
Sn = Tin
Mn = manganese

6. Parts of an atom Atom = basic unit of matter
Every element is composed of one type of atom
Atoms are the smallest pieces of matter that have properties of that element
Composed of protons, neutrons and electrons
Protons (p+): charge of 1+
Neutrons (n0): no charge (neutral)
Electrons (e-): charge of 1-

7. Atomic Components
Protons and Neutrons are located in the nucleus of the atom
The nucleus is positively charged
It is surrounded by a cloud containing electrons
Atoms of different elements differ in the number of protons

8. Atomic Components

9. Subatomic Particles in a neutral atom Most of the atom’s mass.
NUCLEUS
ELECTRONS
in a neutral atom
PROTONS
NEUTRONS
NEGATIVE CHARGE
POSITIVE CHARGE
NEUTRAL CHARGE
Most of the atom’s mass.
Atomic Number
equals the # of...

10. Subatomic Particles
Quarks: very small particles that make up protons and neutrons
Scientists have confirmed 6 different quarks
To study quarks scientists accelerate particles and smash them into protons
The collision breaks apart the proton

11. Atomic Models How small are atoms??
24,400 atoms stacked on top of each other = the thickness of a piece of foil
Scientists create scaled-up models to help visualize atoms
Models are based on indirect evidence
There have been many different models over the years

13. Electron Cloud Model The model now used is the Electron Cloud Model
The electron cloud is the area where electrons are MOST likely to be found
It is 100,000 times larger than the diameter of the nucleus
Ex. Paperclip in a football stadium

14. Orbital Region where there is 90% probability of finding an electron.
Can’t pinpoint the location of an electron.
Density of dots represents degree of probability.
Which area is the most dense?

15. Orbital
Orbitals have different shapes.

16. Inside the Cloud Electrons are various distances away from the nucleus
Closer energy levels have less energy and can hold fewer electrons
Ex. The closer you sit to the teacher in your class, the less you can move around.
Each energy level (n) can hold 2n2 electrons.
Energy Level
Max # of Electrons 1 2 8 3 4 18

17. Ch. 2 – Basic Chemistry continued…
II. Masses of Atoms
Atomic Mass
Mass Number
Isotopes

18. Atomic Mass Particle Mass (g) Electron 9.1093x10-28 Proton
Which subatomic particle weighs the least?
Particle
Mass (g)
Electron
9.1093x10-28
Proton
1.6726x10-24
Neutron
1.6749x10-24
Most of the mass is here!

19. Atomic Number
The atomic number of the element is the same as the number of protons the element has
Elements are put in order of the atomic numbers on the periodic table
The number is the same for every like atom – All Carbon atoms have 6 protons, so, the atomic number of carbon = ____
How many protons does Oxygen have? ____ 6 8

20. Mass Number Also called atomic mass number
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Sum of the protons and neutrons in the nucleus of an atom
Always a whole number.
# of neutrons = mass # - atomic #

21. Number of Electrons
The number of electrons is equal to the number of protons in a neutral atom.
The number of electrons can change, but it doesn’t change the properties of the atom
If an atom loses or gains an electron, it is called an ion.

22. Summary equations # of protons = atomic number
# of electrons = atomic number, unless it’s an ion
# of neutrons =
mass number – atomic number
Atomic mass = # of protons + # of neutrons

23. Isotopes Mass # Atomic # Isotope symbol: “Carbon-12”
Atoms of the same element with different numbers of neutrons.
Isotope symbol:
Mass #
Atomic #
“Carbon-12”

24. Isotopes
Draw Carbon -12, write down how many protons, electrons and neutrons are present. Also, label an electron, proton, neutron and nucleus.
Protons = 6
Neutrons = 6
Electrons = 6
electrons
neutrons
protons
nucleus

25. Isotopes
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26. Isotopes Average Atomic Mass reported on Periodic Table
weighted average of all isotopes
Avg.
Atomic
Mass

27. Isotopes
EX: About 8 out of 10 chlorine atoms are chlorine-35. Two out of 10 are chlorine-37.
Avg.
Atomic
Mass
35.4 g

29. Metallic Character
Metals
Nonmetals
Metalloids

30. Columns & Rows
Group (Family) - Vertical
Period - Across

31. Periodic Trends Group # = # of valence e- (except He)
Groups have similar reactivity.
Period # = # of energy levels 1A 2A
3A 4A 5A 6A 7A 8A

32. BOHR DIAGRAMS Picture representation of an atom
Shows information about the nucleus
Shows electron energy levels

33. How to draw Bohr Models Draw small circle and inside circle, write
Element symbol
# of protons
# of neutrons
Look up what period the element is in (what row) and draw that many circles around your smaller circle
Add electrons as small dots to each circle that is allowed, until you have the proper number of electrons
Remember your number of electrons should equal the number of protons

34. Bohr model of Carbon-12 C
p+=6
N0=6

35. Term: Valence Electrons
e- in the outermost energy level
Except for transition metals
(The middle section of the table)

36. Lewis Dot Diagrams One – So, Sodium has one dot
Dots represent the valence e-
(Electrons in outer level)
How many valence e- does sodium have?
One – So, Sodium has one dot
Ex. Sodium

37. Lewis Dot Diagram 17th 7 What group is Chlorine located?
How many e- are in Chlorines outer energy level? (Draw it to find out) 7
Ex. Chlorine

38. Lewis Dot Diagrams Are useful to show how chemical reactions occur
For example, sodium has 1 valence electron and chlorine has 7 valence electrons
Sodium will give chlorine the extra electron, forming a chemical bond, and forming sodium chloride or tablesalt.

39. H2O Chemical Formula 1 oxygen atom 2 hydrogen atoms Shows:
1) elements in the compound
2) number of the atoms of each element in the compound
H2O
1 oxygen atom
2 hydrogen atoms

40. Chemical Bond
Strong attractive force between atoms or ions in a molecule or compound.
Ion – Charged particle
Formed by:
transferring e- (losing or gaining)
sharing e-

41. Stability
Octet Rule
most atoms form bonds in order to have 8 valence e-
full outer energy level
like the Noble Gases! Ne
Stability is the driving force behind bond formation! (This makes the atoms happy!! )

42. Stability
Which atoms are more likely to gain an electron? Which ones are more likely to lose an electron?

43. Gain or Lose??? Gain Lose Nitrogen Lithium Oxygen Beryllium
Fluorine Boron
Phosphorus Sodium
Sulfur Magnesium
Chlorine Aluminum

44. Stability
Transferring e-
Sharing e-

45. Gain or Loss of e-
Ion- charged particle that has lost or gained an electron
Positively Charged (cations)- Lost electron (remember we like cats!) K+
Negatively Charged (anions)- Gained electron
I -

46. Gain or lose of e- Think about it….. ~ Each e- has a charge of -1,
If you ADD one e- to an atom you have a charge of -1, = -1
~ What if you add 2 e-? -2
~ What if you subtract a charge of -1?
0 – (-1) = +1 (Take away a neg charge)

47. Ionic Bond Attraction between 2 oppositely charged ions
Transfer of electrons takes place
The compound now has a neutral charge
Sum of
charges equal
Zero

48. Ionic Bonds Bond usually forms between metals and non-metals
***Usually the elements are across the table from each other***

49. Covalent Bond Some atoms are unlikely to lose or gain electrons
Instead they share e- between two nonmetals
Creates a molecule
Only form between
Nonmetallic elements
**usually two elements
From the right side of
The table bonded together**