Unit #1Unit #2Unit #3Unit #4Unit #5Unit #6Unit #7Unit #8Unit #9Unit #10
spacerUNIT # 4  
spacerspacerIntroduction
spacerspacerObjectives
spacerspacerReading


spacer4.1 The Periods
spacer4.2 The Groups
spacerGroup IA - Alkali metals
spacerGroup IIA - Alkaline earth metals
spacerGroup VIIA - Halogens
spacerGroup VIIIA - Noble gases
spacer4.3 Metals,
spacerNonmetals,
spacerSemimetals

spacerProperties of Metals
spacerProperties of Nommetals
spacerProperties of Semimetals
spacerSummary
spacer4.4 Metallic
spacerBonding

spacer4.5 Octet
spacerRule

spacer4.6 Ions
spacer
4.7 Covalent
spacerBonding

spacerCovalent Bonding & Groups
spacer
4.8 Atomic
spacerSize

spacer
4.9 Ionic
spacerSize

spacerIonic Size of Metal Ions
spacerIonic Size of Nonmetal Ions
spacerIonic Size for Isoelectronic Series
spacer
4.10 mp/bp
spacerTrends
spacer
4.11 Metallic
spacerTrend


spacer** More
spacerspacerperiodic
spacerTrends
**


spacerspacerProblems
spacer1 | 2 | 3
spacerspacerCrossword
spacerspacerHow well do you
spacerknow your
spacerPeriodic Table?

Unit #4 THE PERIODIC TABLE

4.8 - Atomic Size

The atom does not have a definite boundary. In order to determine the exact radius, r, of an atom, it is necessary to think about this in terms of the chances of finding an electron at a distance r from the nucleus.

Take a look at the image to the right, the bluish-grey colour gradient represents the electron cloud that surrounds the atom. The nucleus resides at the center of the atom. The colour gradation represents the probabilities or chances of finding the electron around the nucleus. The darker the electron cloud, the higher the probability of locating electrons in that volume of space.

As one moves outward from the nucleus, the distance, r, increases. The chances of locating electrons at a greater distance from the nucleus will become less. Therefore, the atom size is based on the average distance between the outer electrons and the nucleus.

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