Atomic BondingAtomic Bonding

Ch 19 sects1 & 2Ch 19 sects1 & 2

Combining ElementsCombining Elements

Elements that are unstable will combine Elements that are unstable will combine with other elements to become stablewith other elements to become stable– Unstable = Wants to change = ready to reactUnstable = Wants to change = ready to react– Stable = wants to stay the sameStable = wants to stay the same

Elements that have combined to be stable Elements that have combined to be stable are known as compoundsare known as compounds

Compounds take on new propertiesCompounds take on new properties– Properties-The way it looks and behavesProperties-The way it looks and behaves

Examples of Compounds andExamples of Compounds andNew propertiesNew properties

Na in water is highly reactive (Metal)Na in water is highly reactive (Metal)Sodium and WaterSodium and Water

Chlorine is highly reactive (gas)Chlorine is highly reactive (gas)

Sodium and Chlorine are unstable Sodium and Chlorine are unstable elements that combine to become stable elements that combine to become stable (table salt)(table salt) When Na and Cl combine to form NaCl the When Na and Cl combine to form NaCl the

new chemical properties cause it to become new chemical properties cause it to become stable and it only dissolves in waterstable and it only dissolves in water

Chemical FormulasChemical Formulas

Chemical formulas are used to show Chemical formulas are used to show which elements are in a compoundwhich elements are in a compound

Chemical formulas also tell you how much Chemical formulas also tell you how much of each element is involvedof each element is involved

CC1212HH2222OO1111 = Sucrose (cane sugar) = Sucrose (cane sugar) Which elements are part of sucrose?Which elements are part of sucrose? How many of each element form sucrose?How many of each element form sucrose?

Atomic StabilityAtomic Stability

Atoms want a full outer valence so they Atoms want a full outer valence so they can become stablecan become stable

Atoms will gain, lose, or share electrons to Atoms will gain, lose, or share electrons to become stablebecome stable

The elements in column 8 (18) on the The elements in column 8 (18) on the periodic table have full outer valencesperiodic table have full outer valences These elements are known as noble gasesThese elements are known as noble gases These elements are chemically stableThese elements are chemically stable

Factors That Affect Bonding Factors That Affect Bonding

How many electrons the atom needsHow many electrons the atom needs If an element only needs to gain/lose 1 If an element only needs to gain/lose 1

electron it will usually form an ionic bondelectron it will usually form an ionic bond The electronegativity of the elements The electronegativity of the elements

involvedinvolved Electronegativity describes how bad an Electronegativity describes how bad an

atom wants an electron/How strong is its atom wants an electron/How strong is its pullpull

Using Electronegativity Using Electronegativity

• Find the electronegativity of the elements forming the bond

• Larger electronegativity (minus) smaller electronegativity (should always be a positive number)

• Find what type of bond it is (Listed above the chart)

Types of BondsTypes of Bonds

• There are 2 major types of bonds There are 2 major types of bonds 1.1. Covalent bonds-Elements share Covalent bonds-Elements share

electrons to have a full outer valenceelectrons to have a full outer valence– Covalent bonding will be broken down into Covalent bonding will be broken down into

two more categoriestwo more categories

2.2. Ionic bonds-Elements give or take Ionic bonds-Elements give or take electrons electrons – Remember when an element changes its Remember when an element changes its

number of electrons it also changes its number of electrons it also changes its overall chargeoverall charge

Covalent BondingCovalent Bonding

Covalent bonding is the sharing of Covalent bonding is the sharing of electrons and it is broken into two electrons and it is broken into two different typesdifferent types

1.1. Non-polar Covalent Bonding-Equal sharing Non-polar Covalent Bonding-Equal sharing of electronsof electrons Elements have a similar electronegativityElements have a similar electronegativity Because the electrons are shared evenly there Because the electrons are shared evenly there

is no change in the charges of the atomsis no change in the charges of the atoms

Covalent BondingCovalent Bonding

2.2. Polar Covalent Bonding-Atoms are shared Polar Covalent Bonding-Atoms are shared unequally between atomsunequally between atoms One atom will have a greater electronegativityOne atom will have a greater electronegativity The atom with the greater electronegativity will The atom with the greater electronegativity will

have a stronger pull on the electronhave a stronger pull on the electron Since the electron spends more time around one of Since the electron spends more time around one of

the elements that element will have a slight (-) the elements that element will have a slight (-) chargecharge

Ionic BondingIonic Bonding

• Ionic bonding forms when one atom gives up an electron and another atom takes that electron– Forms between an atom with a weak

electronegativity and an atom with a strong electronegativity

• Usually between a metal and non-metal• Usually between atoms from the right side of the

periodic table and the left side of the periodic table

Ionic BondIonic Bond

• forming an ionic bond