Chemical Bonding

Alabama Course of Study 5.) Differentiate between ionic and covalent bonds. 5.1 Illustrating the transfer or sharing of electrons using electron dot diagrams

Chemical Bonding Chemical Bonding- combining of atoms to form molecules or ionic compounds Chemical Bond- what holds the atoms together

More info about Atoms Energy level- holds the electrons in orbit around the nucleus 1 st energy level 2 nd energy level 3 rd energy level

Energy Level 1 st energy level- holds up to 2 electrons 2 nd energy level- holds up to 8 electrons 3 rd energy level- holds up to 8 electrons

The goal of an atom The goal of an atom is to be “happy” with a full outer energy level The outer energy level electrons are called valence electrons

How many valence electrons does this need to be “happy?”

Ionic Bonding Ionic Bonding- bond that forms when electrons are transferred from one atom to another This type of bond occurs between metals and nonmetals Ions- charged particles that form when an atom gains or loses electrons

These are both the same element. How? This is what it is in natureThis aluminum has lost 3 electrons but this is unstablebut it is stable and “happy” AlAl Protons13+Protons 13-Electrons10-Electrons O Charge3+ charge

Here is one that gained electrons Oxygen AtomOxygen Ion 8+Protons8+Protons 8-Electrons10-Electrons 0 charge2- charge 00 -2

Now you try 1.Name the 1 st element 2.Find out the # of Protons on both 3.Find the # of electrons on both 4.Subtract the two 5.The solution is the superscript on the Atom Symbol

Try again?

How to show an ionic bond Remember the electrons are transferred

Try doing Ca and S

Covalent Bonds Covalent bond- formed when atoms share one or more pairs of electrons these form molecules This type of bond is between nonmetals ONLY Shared Electrons

Covalent Bond H20H20

How to draw Electron Dot Diagram Step 1: Write down Element symbol Step 2: Find out how many valence electrons there are Step 3: Dispense electrons around the symbol one at a time and if there is enough double up O 6 Valence Electrons

Some common Examples Now try doing Lithium, Boron, Aluminum, Sulfur, and Calcium

Using Electron Dot Diagrams to show Bonds You draw the Electron Dot Diagrams as normal If two elements are sharing an electron it will be on the same side (see below)

Water has a covalent Bond

Some elements have triple or double Bonds

Now try drawing some on your own! NH 3 H 2 S CH 4 F 2 Cl 2 NaCl Si0 2 P 2

How increasing it affects the chemical reaction? Why? Temperature Concentration Surface Area Catalyst

Some Visuals School/BuildingBlocks/BuildingElements.h tmlhttp:// School/BuildingBlocks/BuildingElements.h tml

Chemical Reactions Chemical Reactions- process by which one or more substances change to produce one or more different substances

Temperature A higher temperature causes a faster rate of reaction The higher temperature causes the particles to collide and this releases a lot of energy Some reactions must have heat to react with each other

Concentration A higher concentration of reactants cause a fast rate of a reaction The particles are more likely to bounce into each other if the concentration is higher and increases the rate of the chemical reaction

Surface Area Increasing the surface area of solid reactants increase the rate of the reactions By increasing the surface area, it exposes the amount of the particle to “see” other particles

Catalysts Catalyst- speeds up a reaction without being changed The rate of a reaction increases with catalysts A catalyst is not consumed so it is not a reactant