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Chapter 4 Lecture Notes

Chapter 4
The Chemical Basis of Life

 

Define the following Key Terms:

•          Matter

•          Element

•          Trace element

•          Compound

 

•          An element is a pure substance that cannot be broken down into other substances by chemical means.

•          Examples of some common elements are:

                Gold, Helium, Mercury and Oxygen.

•          See Figure 4.1- Percentages of elements in the human body

Nitrogen                                        Hydrogen

Carbon                                            Oxygen

Calcium                                                           Phosphorous

Sulfur                                             Sodium

Chlorine                                       Magnesium

 

•          Each Element has a symbol e.g.

H=Hydrogen, Li=Lithium, Fe=Iron and O=Oxygen

•          Write the symbols for:

Sulfur:

Potassium:

Argon:

Carbon:

 

Group Activity!

For a Grand Prize!!!

 

Write the element represented by the symbol:

Sn

Write the element represented by the symbol:

Xe

Write the element represented by the symbol:

Rn

           Write the element represented by the symbol:

Ca

Write the symbol that represents the element:

Potassium

Refer to your Periodic Table

 

                                                                                                                                                                       

•          Elements are classified as either a Metal, Non-meal or Metalloid.

•          Metals: luster, good heat and electrical conductivity, malleability, and ductility.


           Non-metals: (the definition is the exact opposite of the one for Metals)

•          Metalloids: have some of the chemical properties of a metal but not all.

 

Compounds

•          Examples of compounds include:

H2O =Water

NaCl  = Table Salt

CO2 = Carbon Dioxide

A compounds properties differ from its component elements ( See Figure 4-2)

 

Compound or Element?

 

Co     CO

H     H200

Li     Mg

 

4.1
Assessment

•          Complete 4.1 concept check questions 1-3

•          You may answer on the same sheet of paper as your notes.

•          Answer in complete sentences.

•          We will go over the questions together in class.

 

4.2
Chemical properties are based on the structure of atoms.

  Define the following Key Terms:

Atom

Proton

Electron

Neutron

Nucleus

Atomic Number

Isotope

Radioactive isotope

 

The structure of an Atom

  •   Protons have a positive charge (+)
  • Electrons have a negative charge (-)
  • Neutrons have no charge (they are neutral)
  • Protons and Neutrons are found within the atoms nucleus. Electrons float outside the nucleus in the Electron cloud. (see fig 4-4)

 

  •  To find the number of Protons and electrons an element has, simply look up the atomic number.
  • How many protons & electrons does:

Neon have?

Oxygen have?

Sulfur have?

 

  •   To calculate the number of Neutrons an element has subtract the atomic number from the atomic mass.
  • Example (F) Fluorine has an atomic number 9 and  an atomic mass of 18.9 (round to 19)
  • 19-9- 10. Fluorine has 10 Neutrons.

 

Group Game Part 2

This time its personal

 

  •   Write the symbol for:

Chlorine

  • Calculate how many protons, neutrons and electrons it has and tell  if it’s a metal, non metal or metalloid.

 

  •   Write the symbol for:

Calcium

  • Calculate how many protons, neutrons and electrons it has and tell  if it’s a metal, non metal or metalloid.

 

  •   Write the symbol for:

Argon

  • Calculate how many protons, neutrons and electrons it has and tell  if it’s a metal, non metal or metalloid.

BONUS QUESTION!!!

  •   Write the symbol for:

Tungsten

  • Calculate how many protons, neutrons and electrons it has and tell  if it’s a metal, non metal or metalloid.

Isotopes

 

  •   Isotopes of an element have the same number of protons in their atoms but a different number of neutrons. (See Fig. 4-5)
  • Radioactive isotopes are used in medical research by allowing scientists observe what happens to different atoms within organisms. (fig 4-6)

 

 

4.2
Assessment

 

  • Complete 4.2 concept check questions 1-4
  • You may answer on the same sheet of paper as your notes.
  • Answer in complete sentences.
  • We will go over the questions together in class

 

 

 

 

                                                                                                                                                                       

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