Atomic Structure and Chemical Bonds Chapter 6 Atomic Structure and Chemical Bonds

Foldable 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 Group 17- Halogens 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 Polar Bond 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: If Two Letters: If Three Letters: 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 H2 Superscript Subscript Chemical Symbol

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