7 th grade. 7th grade science pisd powerpoint lessons developed by ryan gross, park crest middle...

7th Grade

7th Grade Science

PISD PowerPoint Lessons

Developed ByRyan Gross, Park Crest Middle School

Edited ByKenn Heydrick, Coordinator of Science & Health

© Fall 2005, Pflugerville ISD, 8th Grade Unit A: Chapter 3

Chapter 3 - Understanding the Periodic Table

Section 1:Electrons and the Periodic Table

Section 2:Grouping the Elements


Why Do I Need the Periodic Table?

What does your outer shell of clothing say to other people about you

and who you are?

What Do You Think?


Electrons & the Periodic Table

Energy Levels

Electrons in all atoms are arranged around the nucleus in regions called energy levels

•The largest atoms have as many as seven energy levels



Energy Levels

The outermost energy level is called the valence shell

The electrons in the valence shell are called valence electrons



Elements are grouped because they have similar properties

In some groups, the elements all have the same number of valence electrons in their atoms



In atoms of elements in Groups 1 & 2, the number of valence electrons matches the group number



In atoms of elements in Groups 13-18, the number of valence electrons is 10 fewer than the group number



Atoms of elements in Groups 3-12, the Transition Metals, do not follow a general rule

•In addition, helium atoms only have 2 valence electrons


Why Do I Need the Periodic Table?

What similarities exist between you and the other members of

your family? How about between you and your

classmates?

What Do You Think?


Grouping the Elements - Group 1

Group 1: Alkali Metals-1 Valence Electron All metals

except Hydrogen, the Group 1 elements, are the most reactive.



Group 1: Alkali Metals-1 Valence Electron This means that

the atoms of these elements are not stable and will lend valence electrons to other atoms.



Group 1: Alkali Metals-1 Valence Electron

These elements are never found uncombined in nature.



Alkali Metals Compounds formed from Alkali metals have many uses for humans

•NaCl, or Sodium Chloride, is table salt that is used to season your food

•Potassium compounds are found in bananas



Group 2: Alkaline-Earth Metals- 2 Valence Electrons

Alkaline-Earth metals are very reactive, but not as reactive as Alkali metals.



Group 2: Alkaline-Earth Metals- 2 Valence Electrons This is because

it is harder for their atoms to lose 2 valence electrons than for the Alkali metals to lose 1



Group 2: Alkaline Earth Metals

•Magnesium is mixed with other metals to make rims on cars.

•Calcium is an important part of the compound that keeps your bones and teeth healthy.


Grouping the ElementsGroups 3-12

Groups 3-12: Transition Metals

Groups 3-12 do not have individual names.


Groups 3-12

Groups 3-12 Groups 3-12 are all grouped together as the Transition Metals.


Groups 3-12

Groups 3-12 The Transition Metals are less reactive than Groups 1 & 2 because they don’t lose their valence electrons as easily.


Grouping the Elements

Silver and Gold are Transition Metals.


Grouping the Elements

Transition Metals

Iron, Cobalt, and Nickel, all Transition Metals, are the only elements known to produce a magnetic field.


Group 13

Group 13: Boron Group

The most common element from Group 13 is aluminum.


Group 13

Aluminum was considered more precious than gold or silver until the 1880s, when plentiful electricity made it cheaper.

•Aluminum is used to make cans, cars, and airplanes.


Group 14

Group 14: Carbon Group

The nonmetal Carbon, in Group 14, is often found uncombined in nature.


Group 14

Carbon forms both diamonds and charcoal.

Carbon also forms a wide variety of compounds such as proteins, fats, and carbohydrates, all necessary for life on earth.


Group 15

Group 15: Nitrogen Group

Nitrogen, a gas at room temperature, makes up about 78% of the air you breathe.


Group 15

Group 15: Nitrogen Group

Nitrogen from the air is combined with Hydrogen to make fertilizer.

Fertilizer helps grow the crops that feed us all.


Group 16

Oxygen, in Group 16, makes up about 21% of the air you breathe.

Oxygen is very reactive, combining with many other elements such as iron and carbon.


Group 16

Sulfur, another common member of Group 16, is used to make sulfuric acid for car batteries.


Group 17

Halogens are the very reactive nonmetals in Group 17.

They react easily because their atoms only need to gain 1 electron to have a complete set


Group 17

Chlorine is a yellow halogen that is used to disinfect water for drinking and swimming


Group 18

Noble gases are unreactive nonmetals in Group 18.

These elements’ atoms have full outermost energy levels, and cannot react with other elements


Group 18

Noble gases like neon glow when electrically charged.

Argon in a light bulb keeps the filament from burning out.


Let’s Review!

- 1 -

How does the periodic table help you identify the physical

properties of elements?


Let’s Review!

- 2 -

How are elements grouped on the periodic table of

elements?

7 th grade. 7th grade science pisd powerpoint lessons developed by ryan gross, park crest middle...

Documents

pflugerville isd

elements group

periodic table elements

group number slide

number of valence electrons

periodic table section

valence shell

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