Unit 4 – Fundamentals of Chemistry Notes

1. Unit 4 – Fundamentals of Chemistry Notes Compounds and Bonding Remember!!! An __________________ is a substance that cannot be changed into simpler substances under normal laboratory conditions. (Ex:__________________________________) A ________________ is a substance made from the ___________ of different _____________ bonded together in whole-number ratios. (Ex:____________________________________) ________________ ______________ be separated into simpler substances during a _________________ ______________. There are three types of _________________: ___________________, ________________ and _____________________. element Cu, Mg, Ne, H, Al compound atoms elements H2O, CCl4, NaCl Compounds CAN chemical reaction compounds ionic molecular metallic

2. molecular bonded The word ____________________ refers to the smallest __________________ group of atoms that is ___________________ ________________ and acts as a ______________. _____________________ ____________________ are usually made up of two __________________ atoms that are bonded together. When the two atoms are the same, they are known as ___________________ __________________. (Di means __________, so something that is _______________ would be made of how many atoms? ___________ _____________ ions have ___________ ____________) There are _____ ______________ ________________: ( _______ ________ _______ _______ ________ _______ ______) unit electrically neutral Molecular compounds nonmetal molecules two diatomic triatomic 3 many atoms 7 diatomic polyatomic F2 elements H2 O2 N2 Cl2 Br2 I2

3. _______________ compounds are formed when atoms of a _______________ and a _______________ are bonded together. ___________________ bonds are formed between _____________________ ___________________. The true difference between ____________, ___________ and _____________ compounds is: _____________________________________________________________________________ This causes the three compounds to have different physical and chemical properties! Ionic metal Metallic nonmetal two metals molecular ionic metallic the elements involved in the compound

4. Characteristics of Ionic, Molecular and Metallic Compounds Property Ionic Compound Molecular Compound Metallic Compound  Elements Involved Type of Bond Structure  Melting/Boiling Point  Electrical Conductivity  Solubility in Water Physical Descript. of Solids metal/nonmetal 2 nonmetals 2 metals ionic covalent metallic no specific shape crystals crystals generally high generally low generally low hard and brittle soft and mushy malleable & ductile conduct when dissolved in H2O conduct elect. do not conduct not soluble not soluble generally soluble

5. _______________ and _____________ compounds are held together by two types of bonds:__________________ and __________________. _____________ compounds are held together by _____________ bonds. The two main types of bonding studied in this course are:_________________ and ________________________. Ionic molecular ionic covalent Metallic metallic ionic covalent

6. Ionic Bonding When an atom or _____________of atoms ______________ or ____________ an electron, it becomes an ______________. An ion is written like this:_____________. gain groups lose ion Mg2+ How many electrons has the Na atom lost?_________________________ 1 = Na1+ or Na+ What would an ion of Cl that has gained one electron look like?______________ Cl1- or Cl- metal electrons Atoms of ________________ elements tend to lose ___________and become ____________. cations (positively charged ions) Atoms of ________________ elements tend to gain ___________ and become ____________. ionic bonds nonmetal electrons anions (negatively charged ions)

7. When ions of _________________ bond to ions of ________________, they form nonmetals metals _______________ __________________. These compounds are held together by ionic compounds _______________ __________________ and must be ________________. neutral electrostatic forces That means that the charge of the _________________ must equal the charge of the cations ________________. How do we figure this out???ionic bonds anions

8. METHOD 1: Charge balance: Determine the ionic compound formed when Mg bonds to Cl. a)     Step 1: Determine the number of electrons Mg is likely to ________ in a reaction: ( This is known as the ________________ _____________. R Remember the pattern???) P Pattern: lose oxidation number

9. Po At H Oxidation Numbers He +3 +/-4 –3 –2 –1 0 +1+ 2 B Various Si As Ge Te Sb

10. 2 Number of electrons likely to be lost by Mg:__________________ b) Step 2: Determine the number of electrons Cl is likely to _________ in a reaction: ____________________ gain 1 Step 3: Write the two ions that would result if this were to occur: Mg2+ Cl- a)     Step 4: Determine the number of each ion needed to balance the charge: ___________ Mg2+ _____________ Cl1- (or just Cl-) 2 1

11. OR Cl- Mg+2 Cl- atoms a)     Show this as the number of____________ of each element:__________________ You have now written your first ______________ _______________. MgCl2 The small numbers are called subscripts! formula chemical

12. Method 2: Lewis Dot Structures: Step 1: Draw the L.D.S for Mg and Cl. a)     Step 2: Show how Mg will donate an electron to Cl. b)    Step 3: Add another Cl to receive the last electron donated by Mg. Represent the drawing using a chemical formula.

13. For an __________________ _________________, a _____________ _____________ is the lowest whole-number ratio of ________________ in the compound. You would not write __________________ to represent ____________________. This is ________________ for ionic compounds!!! To name ionic compounds, use the name of the _______________ plus the name of the ________________ + ide. (Think of it like this: if it ends in –ine change the n to a d.) (Examples: S = _____________, C = _____________, O = _____________) compound unit ionic formula atoms Mg2Cl4 MgCl2 ONLY metal nonmetal F = fluorine – change n to d = fluoride sulfide oxide carbide

14. Let’s practice!!! 1)     Give the chemical formula for the ionic compound Sodium sulfide. Formula:_____________________ Na2S

15. NOTE!!! Some ions have _____________ ______________ ________________ and must be named differently! For example, _________ can lose ________ or _________ electrons. A compound with _____________ in it must be named using ____________ ___________. If the compound was formed between Fe2+ and S2-, the resulting formula would be ________________ and the name would be __________________ NOT _____________________. multiple oxidation numbers Fe 2 3 these ions Roman numerals Iron (II) sulfide FeS Iron sulfide I = 1 II = 2 III = 3 IV = 4

16. Polyatomic Ions ____________ _____________ are tightly bonded groups of _____________ that behave as a _________________ and carry a ______________. Compounds of polyatomic ions are named using the name of the ________________ followed by the name of the _______________ ______________. Formulas are written in the same manner as with _________ _____________ (the way shown above). The only difference is the presence Polyatomic ions atoms unit charge metal polyatomic ion charge balance of _____________________. (OH)2 means ___________ hydroxide ions. This is _______ the same as OH2! Make sure to use _________________ if there is more than _____________ polyatomic ion. Practice: Write the formula for Sodium sulfate. parentheses two NOT parentheses one Na2SO4 Name the following compound: Mg(NO2)2: __________________________ Magnesium nitrite

17. Covalent Bonding Covalent bonds are formed between two ______________________ to create a ___________________ _________________. In a covalent bond, ____________________ are __________________ not ________________ or ______________________. The names given to _____________ _____________ are known as ____________________ _________________ and are based on a system of ________________. To draw a molecular compound, use a Lewis Dot Structure or charge balance. Example: Show the bonding between C and Cl. covalent bonds nonmetals molecular compound electrons shared donated received molecular compounds molecular formulas prefixes

18. To name molecular compounds, use _________________. If there is only one atom of the first element in the compound, you ____________ _____________ use a prefix. If there is ______________ ______________ of the second element, you ___________ use a _________. Look at the ___________, these tell you the ______________ of ___________ of each element. prefixes DO NOT DO only one prefix subscripts number atoms

19. Prefix Number 1 2 3 4 5 6 7 8 9 10 Practice naming: CCl4 mono ___________________________ di Carbon tetrachloride tri tetra penta Practice naming: CO hexa hepta Carbon monoxide __________________________ octa nona deca _____________________________________

20. DO NOT Molecular compounds __________ _________ have to be written with a ________ ___________ ________________. Example:_________________________________________________ least common denominator C6H12O6 (glucose)

21. Double and Triple Covalent Bonds When atoms share electrons, they may bond _________________ or _______________ times. Example: Show the bonding between two atoms of Oxygen using Lewis Dot Structures: This is a ________________bond. two three double Example: Show the bonding between two atoms of Nitrogen using Lewis Dot Structures: This is a _________________ bond. triple

22. Bond Polarity Remember electronegativity? Electronegativity:______________________________________________________________ _____________________________________________________________________________ When two atoms _________________ electrons, there is a tug-of-war going on between the ______________ of atoms. When the atoms in the bond ____________ equally (Ex: When ____________ atoms bond.) the bond is called a _______________ _____________ ___________. When two _____________ atoms are covalently bonded, the bond is called a _______________ ______________ ____________ or a ___________ ___________. The more _________________ atoms will have the ______________ pull and thus acquire a _______________ _______________ charge. The less ___________________ atoms will acquire a __________________ _________________ charge. the tendency for atoms of an element to attract electrons when bonded to other atoms share nuclei share like non-polar bond different polar covalent bond polar bond electronegative greater slightly negative electronegative positive slightly

23. __ Example: A water molecule: In a polar molecule,_____________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ O H H + + the more electronegative atom pulls the shared electrons creating a slightly negative charge on that end of the molecule. The other atoms acquire a slightly positive charge. Ionic bonds are POLAR! Covalent bonds can be polar OR nonpolar! • Calculate the electronegativity difference. (Take the absolute value.) 2. If it is > 0.4, the bond is polar! Molecules can have polar bonds and be non-polar if they are symmetric!

24. Molecular Shape A _____________ ___________ describes the ______________ and ______________ of atoms present in a _________________ or a __________________. It does not describe the ________________ of the molecule. Molecules can be _________________ and look like this: chemical formula number type molecule compound shape linear Be Cl Cl Linear molecules have the formula: AX2 (such as BeCl2)

25. Molecules can be _________ or _______________ and look like this: bent angular Bent/Angular molecules can have the form: A2X (such as H2O) O H H Molecules can be ________________________ and look like this: tetrahedral H Tetrahedral molecules have the form: AX4 (such as CH4) bonding shapes C H H H In a ___________________ molecule, all the angles are _________________. tetrahedral 109.5o