Chapter 6

Atomic Structure and Chemical Bonds

Foldable

• Hamburger fold• Hamburger fold• Cut along the seam• Label top half “ Ionic Bonds”• Label the Bottom Half “Covalent

Bonds”

Key Vocabulary

• Electron cloud• Energy level• Electron dot

diagram• Chemical bond• Ion• Ionic Bond• Compound

• Metallic Bond• Covalent Bond• Molecule• Polar Bond• Chemical Formula

Atomic Structure

• Your desk appears to be solid, but it is mostly empty space…

• Electron cloud- the area of open space around an atom’s nucleus that contains electrons

• The path of an electron is not well mapped. It is actually kind of random

Electron cloud

• Very similar to the blades of a ceiling fan

• It appears that there is a circle rotating when it is a few blades moving at such a fast rate that it creates that image

Electron arrangement

• Although all the electrons are in the electron cloud, some electrons are closer to the nucleus than others

• Energy Levels- different areas for an electron in an atom

• Look at figure 3 on page 163

Number of Electrons

• Each energy level can only hold a certain number of electrons

• Energy Level One- can hold either 1 or 2 electrons

• Energy Level Two- can hold up to 8 electrons

• Energy Level Three- can hold up to 18 electrons

• Energy Level Four- can hold up to 32 electrons

Quick Lab

• Get a magnet and 4 paper clips• Use the magnet to pick up one paper clip—

record observations• Use the magnet to pick up the rest of the

paper clips one at a time—record observations• One at a time remove the paper clips from the

magnet—record observations• Which paper clip was the easiest to remove?

Why?

Energy Levels

• Electrons in energy level one have the least amount of energy and are less likely to leave the atom

• Electrons in energy level 4 have the most energy and are more likely to leave the atom

Periodic Table and Energy Levels

• The number of electrons increases by one as you go across a period

• The number of energy levels increases by one as you go down a column

• “Eight is Great”

The Noble Gases

• All noble gases either have all of their energy levels filled to its maximum or it has eight electrons in its outermost energy level

Quick Check-up

• How many energy levels?• Calcium• Strontium• Boron

• How many electrons in outermost level?• Antimony• Beryllium• Krypton

Periodic Families

• Group 18- Noble Gasses• Do not combine with other elements• Some react slightly, but it is rare

• Group 17- Halogens• Very reactive- only needs one electron to be

stable• Flourine is the most active, outermost shell

is closest to the nucleus• Group 1- Alkali Metals

• Have one electron in outermost shell• Very reactive with halogens

In your Science Journal

• Read and answer the questions in the “Applying Science” article on page 167

Electron Dot Diagrams

• Write Chemical Symbol• Place first dot on top of symbol and

work right until all four sides have a dot or you are out of electrons• Only use electrons in the outermost energy

level. Why?

• Starting back at the top fill in the remaining spaces until you are out of electrons

Chemical Bond

• The force that hold atoms together• Atoms bond in manner which

makes both atoms stable• i.e: both atoms outermost shells will

be arranged like the noble gasses (8 Electrons)

Ionic Bonds

• Ion- result of an atom loosing or gaining an electron and changing its overall charge

• Ionic bond is an attraction which holds ions together

• Compound- pure substance containing two or more elements that are chemically bonded

What happens…

• If Magnesium (+2 charge) meets with chlorine (-1 charge) will they bond? If so, How?

Metallic bonding

• Form when metal atoms share their pooled electrons

• Keeps metals from breaking and makes them malleable

• The outermost electrons travel from one atom to another enabling a current

Covalent Bonding

• The chemical bond that forms between non-metal atoms when they share electrons

• Form a neutral particle• Molecule- neutral particle formed

when electrons are shared

Diatomic Molecules

• Hydrogen• Oxygen• Nitrogen• Fluorine• Chlorine• Bromine• Iodine• Astatine

Double and Triple Bonds

• Sometimes an atom shares more than one electron with another atom

• Look at figure 17 on page 174 for double bond

• When two pairs of electrons make one covalent bond it is called a double bond

Double and Triple Bonds

• Figure 17 also shows a triple bond between 2 Nitrogen atoms

• This occurs when three pairs of electrons are shared covalently

Polar Molecules

• Ball Demo• 2 different sizes, one is positive and one is

negative

• Polar Bond• When atoms of different sizes bond, they

form polar molecules• These molecules do not share the electrons

evenly• The larger atom keeps the electrons more

than the smaller atom

Polar Molecules

• A good example of a polar molecule is water

• Also, hydrochloric acid and sodium chloride• Draw these three molecules and

determine the poles.

Chemical Symbols

• You all have been asking how elements get their symbols

• Most elements are symbolized by their first letter• Examples: Hydrogen (H) and Carbon (C)

• Others are symbolized for their name in another language• Potassium (K) – Latin for Kalium• Iron (Fe) – Greek for Ferrous

• Chemical symbols are understood worldwide

Chemical Symbol Rules

• If One Letter:• Must be capitalized

• If Two Letters:• First letter is capital and the second is

lowercase• If Three Letters:

• First letter is capitalized and the remaining are lowercase

2 H2Superscript

Chemical SymbolSubscript

Common Chemical Formulas• Hydrochloric Acid• Sodium Chloride• Sodium Hydroxide• Sulfuric Acid• Silver Nitrate• Iron Oxide

• Water• Hydrogen

Peroxide• Ammonia• Nitric Acid• Acetic Acid• Magnesium

Chloride