chemistry 1.1

ChemistryChapter 1 - Section 1

Why Do Atoms

Combine???

Monday, July 9, 2012

First, we need to

know what an atom is?


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Atomic Structure


http://www.youtube.com/watch?v=lP57gEWcisY



Atomic Structure


Atomic Structure

All matter, even solids, contain mostly e m p t y space.


Atomic Structure


How can this be?


Atomic Structure


How can this be?

Although there might be little or no space between atoms, a lot of empty space lies within each atom.


Atomic Structure


At the center of every atom is a nucleus containing protons

and neutrons.

Atomic Structure



and neutrons.

The nucleus makes up most of the mass of an atom.

Atomic Structure



and neutrons.


The rest of the atom is empty except for the atom’s electrons,

which are extremely small compared with the nucleus.

Atomic Structure



and neutrons.


The rest of the atom is empty except for the atom’s electrons,

which are extremely small compared with the nucleus.

The exact location of an electron cannot be determined, the electrons travel in an area around the nucleus called the electron cloud.

Atomic Structure


Atomic Structure


Are you ready to be

amazed??


WOW


WOWAtoms are extremely small.



One hydrogen atom is approximately 5x10-8mm in diameter.




Think about a 1 mm line. It would take _______ hydrogen atoms lined up beside each other to make a line as long as the mark.




Think about a 1 mm line. It would take _______ hydrogen atoms lined up beside each other to make a line as long as the mark.

20 million!!!! Monday, July 9, 2012

Electrons and Our Solar System


Planets orbit the sun, just as electrons orbit the nucleus of an atom.




Some differences between electrons and plants are:




Some differences between electrons and plants are:Planets do not have a charge, electrons are negatively

charged




Some differences between electrons and plants are:Planets do not have a charge, electrons are negatively

chargedPlanets orbits are predictable, electron orbits are not

as predictable.



Element Structure

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Element Structure

Each element has a different atomic structure and a different number of protons, neutrons, and electrons.

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Element Structure

Each element has a different atomic structure and a different number of protons, neutrons, and electrons.

The number of protons and electrons is always the same for a neutral atom.

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Electron Energy


Electron Energy

All electrons in an atom are somewhere in the electron cloud.


Electron Energy


Some electrons are closer to the nucleus than others.


Electron Energy



The different areas for an electron in an atom are called energy levels.


Electron Energy




Each level represents a different amount of energy and can hold a certain number of electrons.


Electron Energy




Each level represents a different amount of energy and can hold a certain number of electrons.

The farther an energy level is from the nucleus, the more electrons it can hold.


Energy Steps


Energy Steps

Text


Energy Steps

Text

Level Max. number of electrons1st 22nd 83rd 184th 32


Energy Steps


Energy Level 1 has the lowest amount of energy.

Energy Steps



Electrons furthest away have the most energy.

Energy Steps




Electrons furthest away are the easiest to remove.

Energy Steps





How many electrons can occupy an energy level?

Energy Steps





How many electrons can occupy an energy level?

Use 2n2 (n represents the energy level).

Energy Steps


Magnets & Paper Clips


Magnets & Paper Clips

Removing electrons that are closer to the nucleus takes more energy than removing ones that are further away.


Removing Part of the Balloon


What is being removed from the balloons atoms?




Electrons




ElectronsFrom what energy level?




ElectronsFrom what energy level?

Highest energy level



Our Wonderful and Perfect Periodic Table


Horizontal Rows are called periods

21




21

Period 1




21

Period 1

Period 2




21

Period 1

Period 2

Period 3



Vertical Rows are called Groups or Families

22




22

Group 1




22

Group 1

Group 2




22

Group 1

Group 2

Group 3




22

Group 1

Group 2

Group 3

Group 4




22

Group 1

Group 2

Group 3

Group 5

Group 4




22

Group 1

Group 2

Group 3

Group 5

Group 6

Group 4




22

Group 1

Group 2

Group 3

Group 5

Group 6

Group 7

Group 4




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Group 1

Group 2

Group 3

Group 5

Group 6

Group 7

Group 4

Group 8



Remember that the number of protons and electrons are the same in a neutral atom (which

is what is represented on the periodic table).



Remember that the number of protons and electrons are the same in a neutral atom (which

is what is represented on the periodic table).

The number of electrons increases by one as

you move across the period.




A few things to notice....




Groups 3-12 are not pictured.




Groups 3-12 are not pictured.

Group 18 is complete, it is full. It has _____ electrons.


Hydrogen is usually considered separately,

so the first element

family begins with lithium and sodium in the first column.

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Human family members often have similar looks and traits.



Human family members often have similar looks and traits.

Also, members of element families have similar properties, chemical properties, because they have the same number of electrons in their outer energy levels.



It was the repeating pattern of properties that gave Russian chemist Dmitri Mendeleev the idea for his first periodic table in 1869.



Why so Noble, Group 18?


Noble Gases have energy levels that are complete. They have 8 electrons in their outer energy levels.




Do not combine well with other elements – originally thought they would not combine at all, but they will on rare occasion.





Because they are so stable they are used to protect filaments in light bulbs.





Because they are so stable they are used to protect filaments in light bulbs.

Also used as to produce coloured lights in signs…electricity causes the noble gases to emit a certain colour light. Neon – orange/red; Argon – lavender; Helium – yellowish white



Halogens From Halifax(Group 17)


Halogens only need one more electron, so they are very reactive.




Fluorine is the most reactive because the electrons are so close to nucleus.




Fluorine is the most reactive because the electrons are so close to nucleus. Remember that when electrons are close to the nucleus,

there is a stronger pull from the protons.



The further you go down group 17, the

reactivities decrease.



The further you go down group 17, the

reactivities decrease.This is because there is more energy levels,

and so the electrons are further away from the pull of the protons.



Alkali Metals Have One Extra Petal

(Group 1)


Alkali Metals have one electron in outer most

energy level.


(Group 1)



energy level.

This electron will be removed when alkali metals reacts.


(Group 1)



energy level.

This electron will be removed when alkali metals reacts.

The easier it is to remove an electron, the more reactive the atom is.


(Group 1)



(Group 1)


Reactivities increase as you go down the group. Why?


(Group 1)


Reactivities increase as you go down the group. Why?

Alkali metals want to give away one of their electrons. That electron is further away from the pull of the proton as you move down group 1 in the periodic table.


(Group 1)


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Electron Dot Diagrams



An electron dot diagram is the symbol for the element surrounded by as many dots as there are electrons in its outer energy level.



An electron dot diagram is the symbol for the element surrounded by as many dots as there are electrons in its outer energy level.

Only the outer energy level electrons are shown because these are what determine how an element can react.


Start by writing one dot on the top of the

element symbol




element symbol

Then work your way around, adding dots to the right, bottom, and left.




element symbol


Add a fifth dot to the top to make a pair.




element symbol


Add a fifth dot to the top to make a pair.

Continue in this manner until you reach eight dots to complete the level



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