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PSC 4012. Ionic Phenomena: A study of an environmental problem. PSC 4012: Chapter 2. Goals: _ SWBAT describe the current simplified atomic model _SWBAT describe the four most important families of the Periodic Table

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PSC 4012

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Psc 4012

PSC 4012

Ionic Phenomena:

A study of an environmental problem


Psc 4012 chapter 2

PSC 4012: Chapter 2

Goals:

_ SWBAT describe the current simplified atomic model

_SWBAT describe the four most important families of the Periodic Table

_SWBAT use and explain the relationship between electronic configuration and periodical properties


Psc 4012 chapter 21

PSC 4012: Chapter 2

A model is a physical representation of something we cannot see

(even without visible proofs we can demonstrate the existence of objects and explain their nature)


Psc 4012 chapter 22

PSC 4012: Chapter 2

What have we learned about the evolution of the Atomic Model?

Dalton’s (solid indivisible balls, no charge, different masses)

Thomson’s (positive nucleus, embedded with negative electrons)

Rutherford’s (atoms are mostly empty space, most mass is found at nucleus, light electrons surround it)

Bohr’s (electrons revolve around nucleus in fixed levels or shells)


Psc 4012 chapter 23

PSC 4012: Chapter 2

What is the simplified atomic model?

How are the other models added to it?


Psc 4012 chapter 24

PSC 4012: Chapter 2

Simplified Atomic Model

  • Mass of protons is similar to that of neutrons

  • Mass of electrons is negligible (1840 times smaller than mass of protons)

  • Number of protons: Atomic number

  • Number of protons and neutrons: Mass number


Psc 4012 chapter 25

PSC 4012: Chapter 2

Practice Exercises

  • Page 2.6 – Ex 2.1


Psc 4012 chapter 26

PSC 4012: Chapter 2

Simplified Notation

  • Fast way to inform about electronic configuration

  • Each level must be completed before moving to the next one

  • First level: 2e

  • Second level: 8e

  • Third level: 8e

  • Fourth level: 2e (for the purpose of this course)


Psc 4012 chapter 27

PSC 4012: Chapter 2

Simplified Notation

_Figure 2.3 (p. 2.8)

B: 2e, 3e

O: 2e, 6e

Cl: 2e, 8e, 7e


Psc 4012 chapter 28

PSC 4012: Chapter 2

Practice Exercises

  • Page 2.9 – Ex 2.2

  • Page 2.10 – Ex 2.3


Psc 4012 chapter 29

PSC 4012: Chapter 2

Mendeleyev

_Created first Periodic Table (page 2.15)

_Organized elements according to Atomic Mass

_Periodic: Columns of elements with similar properties

_Predicted existence of elements according to observed periodicity (blank spaces in table)


Psc 4012 chapter 210

PSC 4012: Chapter 2

Symbols:

  • You must know the name of the first 20 elements of the Periodic Table (plus a couple of very common metals)

  • Some elements are represented by a capital letter, others by a combination of two (capital and lower capital)

  • Examples: O (Oxygen), Fe (Iron)


Psc 4012 chapter 211

PSC 4012: Chapter 2

Modern Periodical Table

  • 90 natural elements

  • 19 artificial elements

  • Elements are organized according to their atomic number

  • Horizontal rows represent Periods or Energy Levels

  • Vertical rows represent Groups or Families of elements, with similar chemical properties


Psc 4012 chapter 212

PSC 4012: Chapter 2

Atomic numbers


Psc 4012 chapter 213

PSC 4012: Chapter 2


Psc 4012 chapter 214

PSC 4012: Chapter 2

Metals:

  • On the left of dark staircased-type line (except Hydrogen)

  • “Metallic” luster

  • Conduct electricity and heat

  • Solid at room T (except “Hg”, Mercury, liquid)

Non-metals:

  • On the right of dark staircased-type line (also Hydrogen)

  • Do not have shiny luster

  • Do not conduct electricity or heat

  • Mostly gases at room temperature (except “Br”, Bromine, liquid)


Psc 4012 chapter 215

PSC 4012: Chapter 2

Metalloids:

  • Along the staircase line (between metals and non metals)

  • Resemble non metals

  • Conduct electricity and heat


Psc 4012 chapter 216

PSC 4012: Chapter 2

Practice Exercises

  • Page 2.22 – Activity 2.1


Psc 4012 chapter 217

PSC 4012: Chapter 2

Groups (Families)

Group I

Li:2e, 1e

Na: 2e, 8e, 1e

K: 2e, 8e, 8e, 1e

Group II

Be:2e, 2e

Mg: 2e, 8e, 2e

Ca: 2e, 8e, 8e, 2e

Group V

N:2e, 5e

P: 2e, 8e, 5e

Group I

Li:2e, 1e

Na: 2e, 8e, 1e

K: 2e, 8e, 8e, 1e

Group II

Be:2e, 2e

Mg: 2e, 8e, 2e

Ca: 2e, 8e, 8e, 2e

Group V

N:2e, 5e

P: 2e, 8e, 5e

The number of the group (family) tells you the amount of electrons in the last shell


Psc 4012 chapter 218

PSC 4012: Chapter 2

Practice Exercises

  • Page 2.24 – Activity 2.2


Psc 4012 chapter 219

PSC 4012: Chapter 2

Periods

Period I

H: 1e

He:2e

Period II

Li: 2e, 1e

Be:2e, 2e

N: 2e, 5e

Period III

Na:2e, 8e, 1e

P: 2e, 8e, 5e

Cl: 2e, 8e, 7e

Period I

H: 1e

He:2e

Period II

Li: 2e, 1e

Be:2e, 2e

N: 2e, 5e

Period III

Na:2e, 8e, 1e

P: 2e, 8e, 5e

Cl: 2e, 8e, 7e

The number of the period tells you the amount of energy levels for electrons to surround the nucleus


Psc 4012 chapter 220

PSC 4012: Chapter 2

Group IA

  • Alkali metals

  • One electron in outermost shell

  • Very soft to touch

  • Extremely reactive with water, oxygen and halogens


Psc 4012 chapter 221

PSC 4012: Chapter 2

Group IIA

  • Alkaline-Earth metals

  • Two electrons in outermost shell

  • Less soft to touch

  • Less reactive with water


Psc 4012 chapter 222

PSC 4012: Chapter 2

Transition Metals

  • Heavy metals between groups IIA and IIIA


Psc 4012 chapter 223

PSC 4012: Chapter 2

Group VIIA

  • Halogens

  • They have seven electrons in their outermost shell

  • They are very reactive

  • Never to be found alone (if not attached to another element, attached to themselves in diatomic molecules, e.g. Cl2, F2 , etc.)


Psc 4012 chapter 224

PSC 4012: Chapter 2

Group VIIIA

  • Noble Gases

  • They have eight electrons in their outermost shell

  • They are very inert

  • Do not react with anybody, and are considered rare gases for they account for only 1% of gases in atmosphere


Psc 4012 chapter 225

PSC 4012: Chapter 2

Hydrogen

  • One of a kind

  • Lightest and most abundant element

  • Non-metal (gaseous)


Psc 4012 chapter 226

PSC 4012: Chapter 2

Isotopes

Atoms that have the same number of protons (and electrons), therefore they have the same atomic number

(atomic number = # protons)

Atoms that have different number of neutrons , therefore they have differentmass number

(mass number = # neutrons + # protons)


Psc 4012 chapter 227

PSC 4012: Chapter 2

Isotopes notation

The higher the number of neutrons in an isotope, the lower its stability


Psc 4012 chapter 228

PSC 4012: Chapter 2

Practice Exercises

  • Page 2.21 – Ex 2.12 & 2.13


Psc 4012 chapter 229

PSC 4012: Chapter 2

The atomic mass of an element is the result of the mixture of its isotopes in different proportions

The proportion of an isotope is expressed as a percentage, and it is called “relative abundance” (table on page 3.28)

Therefore, in order to calculate the real atomic mass of any element, you have to multiply the mass number of each isotope by their relative abundance percentage, and add them together.


Psc 4012 chapter 230

PSC 4012: Chapter 2

Example:

Knowing that there is a 98.99% of C-12 in nature, a 1.11% of C-13, and traces of C-14, calculate the atomic mass of Carbon (C):

= (12 * 98.99/100) + (13 * 1.11/100) + 14 (0/100)

= 11.8668amu + 0.1443amu

= 12.0111 amu(amu: Atomic Mass Unit)


Psc 4012 chapter 231

PSC 4012: Chapter 2

Need another example of calculations?!

(Table 2.10, page 2.19, Nitrogen)

Knowing that there is a 99.64% of N-14 in nature, and a 0.37% of N-15, calculate the atomic mass of Nitrogen (N):

= (14 * 99.64/100) + (15 * 0.37/100)

= 13.9496amu + 0.0555amu

= 14.0051 amu


Psc 4012 chapter 232

PSC 4012: Chapter 2

Each group’s number is equal to the number of electrons in outermost shell

Modern Periodic Table organized in increasing number of atomic number (or # protons or # electrons)

What have we learned so far?

Each period’s number is equal to the number of energy levels (orbits) of electrons

Metals are found on the left of dark stair cased-type line (except Hydrogen)

Non-metals are found on the right of dark stair cased-type line (also Hydrogen)

Group IA: Alkali metals

Group IIA: Alkaline-Earth metals

Group VIIA: Halogens

Group VIIIA: Noble Gases


Psc 4012 chapter 233

PSC 4012: Chapter 2

Same atomic number, therefore, same number of protons (and electrons)

Isotopes are atoms of the same element, with same atomic number, but different atomic mass (mass number)

What have we learned about isotopes?

Mass number is the closest integer to which atomic mass (a decimal) is rounded up to

Mass number = Atomic number (# protons) +

# neutrons

Atomic mass = (mass number)I1 * (relative abundance) I1 + (mass number)I2* (relative abundance) I2 + ...

+ (mass number)In* (relative abundance) In+


Psc 4012 chapter 234

PSC 4012: Chapter 2

Practice Exercises

  • Page 2.20 – Ex 2.7 – 2.11

  • Page 2.36 – 2.39 Ex 2.18 – 2.26


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