This document discusses the structure of atoms and bonding between atoms. It describes that an atom consists of a nucleus containing protons and neutrons, surrounded by electrons. Atoms bond through either ionic or covalent bonding. Ionic bonding occurs when atoms gain or lose electrons to become ions, forming electrostatic attractions. Covalent bonding occurs when atoms share electrons to achieve stable electron configurations.

7. ATOMICITY OF AN ELEMENT:
No. of atoms present in one molecule of an element.

11. Sub Atomic Particles
• Protons
• Neutrons
• Electrons

12. Atoms are tiny
particles!!
NUCLEUS ELECTRONS
PROTONS NEUTRONS
POSITIVE
CHARGE
ATOM
POSITIVE
CHARGE
PROTONS
NEUTRAL
CHARGE
NEUTRONS
NUCLEUS
NEGATIVE CHARGE
ELECTRONS
ATOM
Mostly empty space!!

13. An atom consists of
• a nucleus (of protons and neutrons)
• electrons in space about the nucleus.
The Anatomy of an Atom
Electron cloud
Nucleus

14. Subatomic
components
Relative
Mass
Charge
nucleus
Proton 1 +1
Neutron 1 0
Orbital
cloud Electron 0.005 -1
Features of the
Atom

15. Protons
• Located in nucleus of atom
• Has a positive charge
• Number of Protons = Atomic Number
• Has 1 AMU in mass (Atomic Mass Unit)
+
+
+

16. Neutrons
• Located in nucleus of atom
• Has NO electrical charge
• Has mass of 1 amu
• Number of neutrons usually is equal to
number of protons

17. Electrons
• Located outside the
nucleus of the atom
• Housed in Electrical
Clouds, Shells, Orbits
• Has a negative charge
• Does not have an amu
because of tiny size
• Moves around the
nucleus in an orbit

18. Quiz – Subatomic
Particles
2.The positive particle is the .
3.The negative particle is the .
4.The neutral particle is the .
5.The proton is the same as the number.
6.The two particles located inside the nucleus
are the and the .
6.Each of these particles
have a mass of .

19. Hydrogen
Atom
Electron
Cloud

20. Quick Quiz – Subatomic Particles
(continued)
7. The electron around the
nucleus.
8. The electrons are the
outer electrons and are involved
in bonding.
9.To find the number of neutrons in
an atom you subtract the
number from the _ number.

21. Mass Number
• mass number A = protons + neutrons
• always a whole number
• NOT the value given on
the Periodic Table!

22. Atomic Number
• atomic number z = protons
• always a whole number
• identifies the element

24. A-Z notation
6
12
C
mass number A
element symbol
atomic number Z
The atomic number
equals the number of
protons. Each element
has a unique atomic
number.

25. Atomic Numbers
• Number used to arrange the Periodic
Table
• Increase Left to Right
• Same as number of Protons or Electrons
in a neutral atom

26. Atomic Mass
• The sum of the Protons and Neutrons
in the nucleus.
• Also called Atomic Weight
Protons
+Neutrons
Atomic
Weight

27. Electron Arrangement
• Electrons orbit the nucleus in
Energy levels
• The first level (or cloud, or shell)
contains up to 2 electrons
• The second level contains up to 8
electrons
• The third level contains up to 18
electrons
• 4th 32; 5th 50; 6th 72 max inshell

29. Electron Distribution in various shell of an Atom

30. Practice:
Lithium has the atomic
number 3
and mass number 7
# of protons:
# of neutrons:
# of electrons:
3
4
3

31. Practice: Lithium has the
atomic number 3 and mass
number 7
– electron arrangement (configuration) 2, 1
Lithium is in Group 1
on the Periodic Table

32. Electron Arrangement ctd.
• The electrons in the
outermost shell (if it is not
completely full) are
available for bonding
• These electrons are called
Valence Electrons
• Bonding is the chemical
combining of 2 or more
atoms.

33. Practice: electron arrangements of the first
20 elements (2,8,8,2)
• Chlorine-37
– atomic #:
– mass #:
– # of protons:
– # of electrons:
– # of neutrons:
17
37
17
17
20
37
17 Cl

34. Ion
s
• ions are electrically charged atoms
Neutral atom
negative ion
positive ion
lose electrons gain electrons
p+ > e-
cation
p+ < e-
anion

35. Practice: determine the
required values for the
positive calcium ion
41 Ca+2
– atomic #:
– mass #:
– # of protons:
– # of electrons:
– # of neutrons:
20
41
20
18
21

36. Isotopes: Atoms of the same element with different
mass numbers.
carbon-12
and carbon-
14 are
isotopes
similar chemical properties
© Addison-Wesley Publishing Company, Inc.
stable
radioactive

37. Quick Quiz – Numbers,
Electron Arrangement
10. The is used to arrange the periodic table asit
increases from to .
11. The atomic number is the same as the number of
.
12. The number is the sum of protons and neutrons
inside the .
13. The outermost electrons are the
electrons and
they orbit the nucleus in levels.
14. Bonding is the combining of 2 ormore

38. Bonding
• The process when 2 or more atoms
combine chemically is known as Bonding
• The 2 we are learning today are
• Ionic Bonding
• Covalent Bonding

39. Ionic Bonding
• Electrons are either gained or lost by
atom
• One atom is positive +, One is negative
-
• Occurs between Metals and Nonmetals
• Metals lose electrons
• Nonmetals gain electrons
• Very strong bond – usually solids - with
high melting temperatures

40. Sodium and Chlorine

41. Sodium – a
soft grey
highly
flammable
metal
Chlorine – a
highly
poisonous
green gas
+

42. =
(equals)
Table Salt

43. Lithium and Fluorine diagram shows
Ionic Bonding in action

44. Common Ionic Bonds
• NaCl Sodium Chloride Table Salt
• CuSo4 Copper Sulfate Kills algae
• NaHCO3 Baking Soda Baking & Health

45. Quiz – Bonding
Ionic
1. In ionic bonding electrons are either.......
or............
2. …...lose electrons and.......gain electrons.
3. A positive ions has ….....electrons and
a …......... negative ion has electrons.
4. ...........bonds are strong, usually solid,
and have........melting and boiling points.
5. The magic number of valence
electrons needed by all.........but two
atoms is …........
6. Name two common ionic bonds.

46. Covalent Bonding
• Electrons are shared between atoms (co)
• Neither atom has an electrical charge
• Forces between atoms are weak – have
low boiling or melting points
• Usually are liquids or gasses
• If a solid is usually a crystal

47. Water
Methane
Methane

48. Common Covalent Bonds
• H2O Water
• CH4 Methane
• C3H8 Propane

49. Quick Quiz – Bonding
Covalent
1. In a covalent bond, electrons are............. .
2. Neither atom has a …................
3. Intermolecular forces
are ..... ...............weak.
4. Covalent bonds have ..............melting and............. points.
5. Covalent bonds are usually found in these two states of matter.
6. Two common covalent compounds are ...............and ….........

50. Ionic – Gain
or Lose
Electrons
Covalent – Share
Electrons