• Save
2 Atomic Structure
Upcoming SlideShare
Loading in...5
×
 

2 Atomic Structure

on

  • 1,996 views

 

Statistics

Views

Total Views
1,996
Views on SlideShare
1,961
Embed Views
35

Actions

Likes
1
Downloads
0
Comments
0

2 Embeds 35

http://antiguaundergraduate.org 34
http://www.slideshare.net 1

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

2 Atomic Structure 2 Atomic Structure Presentation Transcript

  • 2 Atomic Structure
  • Properties of subatomic particles Outside nucleus 0 -1 Electron nucleus 1 0 Neutron nucleus 1 +1 Proton Location Relative mass(amu) Relative charge Name
  • Terminology for the Atom
    • Atomic no (Z): no of protons
    • Mass No (A): no of protons + no of neutrons
    • Isoptopes: atoms of the same number of protons (the same element) but different numbers of neutrons
    • Atomic mass unit: 1/12 the mass of a carbon-12 atom. The mass of a carbon-12 atom is defined as exactly 12 atomic mass units
    • Atomic mass: the average of the masses of an elements naturally occurring isotopes weighted to their abundances
  • Isotope Calculations
    • Boron has 2 isotopes 10 B and 11 B. They are present in naturally occurring boron respectively at 18.7% and 81.3%. Calculate the relative atomic mass of boron.
    Ar = (18.7 x 10) + (81.3 x 11) 100 = 10.8
    • The element copper has relative atomic mass 63.55 and contains atoms with mass numbers 63 and 65. What is the percentage composition of a normal isotope of copper?
    65x + ((100-x) x 63) = 63.55 100 65x + 6300 – 63x = 6355 2x = 6355-6300 x = 27.5% 100 – x = 72.5% % composition = 27.5% 65Cu 72.5% 63Cu
  •  
  • Bonding Terminology
    • Ionic compounds: form when an atom of one element transfers electrons to an atom of another element
    • Covalent compounds: form when two atoms share electrons
    • Ion: a charged particle
    • Cation: a positively charged particle
    • Anion: a negatively charged particle
    • Monoatomic ion: an ion composed of a single aton
    • Polyatomic ion: two or more atoms bonded covalently and having net positive or negative charge e.g. NH 4 + , SO 4 2-
  • Electronic Configuration
    • Electrons are present in shells around the nucleus
    • The first shell can hold 2 electrons, the second 8 and the third 18
    • The no of outer shell electrons is the same as the group no
    • Find the electronic configuration of sodium
    Na atomic no = 11  there are 11 protons and 11 electrons Electronic Configuration is 2,8,1 Find the electronic configuration of chlorine Cl atomic no = 17  there are 17 protons and 17 electrons Electronic configuration is 2,8,7
  • Compounds
    • Ionic compounds are formed between a metal and a non metal e.g. magnesium chloride
    • Covalent compounds are formed between two or more non-metals e.g ammonia (NH 3 )
  • Formation of Covalent Bonds Drawing dot and cross diagrams
    • Only outer shell electrons are shown
    • Dots and crosses used to distinguish electrons from different atoms
  • x o o o o o o o x o o o o o o o H Cl HCl Formation of HCl
    • Draw dot and cross diagrams for methane (CH 4 ), ammonia (NH 3 ) and nitrogen N 2 and carbon dioxide (CO 2 )
    • Elements in Group 1 form unipositive cations e.g. Na +
    • Elements in Group 2 form dipositive cations e.g. Mg 2+
    • Elements in Group 3 form tripositive cations e.g. Al 3+
    • Elements in Group 7 form uninegative anions e.g. Cl -1
    • Elements in Group 6 form dinegative anions e.g. O 2-
    Formation of ionic bonds
    • Na Cl
    x o o o o o o o Na + + Cl - NaCl
    • Mg F
    x x o o F o o Mg 2+ + 2F - MgF 2 o o o o o o o o o o
    • Draw diagrams to represent the ionic bonding for aluminium iodide and sodium oxide
  • Properties of Ionic Compounds
    • High mp/bp
    • Conduct electricity when molten or in aqueous solution
    • Dissolve in polar solvents (eg water)
    • Hard and brittle
    • React readily with each other in solution
  • Covalent Compounds & Structures
    • Covalent compounds may be classed as simple e.g water, ammonia, chlorine, sulphur dioxide, carbon dioxide
    • or as giant e.g. silicon dioxide (sand) diamond, graphite
    • Simple covalent compounds are small molecules held together by Van der Waals forces only
    • Giant covalent structures are giant lattices where every atom is covalently bonded to many atoms
  • Diamond Structure
  • Properties of Simple Covalent Compounds
    • Low mp/bp
    • Non conducting
    • Soluble in non-polar solvents
    • Solids are soft
  • Properties of Giant Covalent Structures
    • High mp/bp
    • Non-conducting (except graphite and some semiconductors e.g. silicon dioxide)
    • Non-soluble
    • Hard (except graphite)