Chapter 5-The Structure of Matter Molecules and Compounds Ionic and Covalent Bonding Naming Compounds

Compounds and Molecules

Remember from Chapter 2… A compound is a substance made of atoms of two or more different elements that are chemically combined by chemical bonds Mixtures are made of different substance that are just placed together; each substance in the mixture keeps its own properties

What is a chemical bond? An attractive force between the nuclei and valence electrons of different atoms that binds them together Bonds form in order to… decrease potential energy (PE) increase stability

Ne Stability Stability is the driving force behind bond formation! Octet Rule most atoms form bonds in order to have 8 valence e- full outer energy level like the Noble Gases! Ne Stability is the driving force behind bond formation!

Becoming Stable All neutral atoms want to be stable like a noble gas They either GAIN or LOSE electrons CATION: Positively Charged ANION: Negatively Charged Na Cl = Loses electron; becomes + Gains electron; becomes -

Becoming Stable CATIONS: Have more positive charge than negative, they LOSE electrons ANIONS: Have more negative charge than positive, the GAIN electrons Na Cl = Loses electron; becomes + Gains electron; becomes -

What’s the charge? The charge on an ion. Indicates the # of e- gained/lost to become stable. 1+ 4- 2+ 3+ 4+ 3- 2- 1-

Stability Transferring e- Sharing e-

Ionic and Covalent Bonding

Covalent Bonds Nonmetal + Nonmetal Bonds form by SHARING ELECTRONS

Ionic Bonds Metal + Nonmetal Bonds form by TRANSFERRING ELECTRONS

What’s the charge? The charge on an ion. Indicates the # of e- gained/lost to become stable. 1+ 4- 2+ 3+ 4+ 3- 2- 1-

How do ions bond? +1 -1 Review: cations + anions What is the ionic charge of Na? +1 What is the ionic charge of Cl? -1 The final compound MUST be neutral!!

Continued… Na+1 + Cl-1 = NaCl (neutral) Cs+1 + O-2 = Cs2O (neutral) Metals Non metals Na+1 + Cl-1 = NaCl (neutral) It takes 1 positive Na to balance the 1 negative Cl Cs+1 + O-2 = Cs2O (neutral) It takes 2 positive Cs to balance the 1 negative O We use the subscripts to depict how many atoms of each element must be used for the compound

Crossing Charges Na+1 + Cl-1 Na Cl = NaCl Switching the superscripts to make new subscripts also works: Na+1 + Cl-1 Na Cl = NaCl

Try these… Cs+1 + O-2 = Mg+2 + S-2 = Be+2 + N-3 =

Not all ions are single elements: Different ions Not all ions are single elements: We’ve seen some ions made of single elements, but… Some are made of more than a single element (polyatomics) SO4-2 CO32- OH- NO3- More than 1…atom

Naming binary ionics (nomenclature) Write the name of the cation (metal), just the way it is Write the name of the anion (non metal), change the ending to “ide” Nitrogen – nitride Oxygen – oxide Chlorine – chloride Carbon - carbonide

Name the following compounds: Lets practice…!! Name the following compounds: MgCl CaBr2 CaO SrF2

Give compound formulas for the following: Let’s practice more…!! Give compound formulas for the following: Potassium iodide Aluminum sulfide Sodium chloride Magnesium nitride

Naming compounds with polyatomic anions Write the name of the cation (metal), just the way it is Isolate the polyatomic anion – determine its name Write the name of the polyatomic anion, just the way it is The ones to the right are the ones you need to know

Name the following compounds: Let’s practice…!! Name the following compounds: Ca(OH)2 Na2(CO3)

What about polyatomics that look similar, but are different Most polyatomic look very similar, but have different numbers of oxygens SO3 and SO4 Is a trick to it Hypo – “little” Ite Ate Hyper – “lots”

That’s right, more practice…!! Name the following compounds: Na (ClO3) Na(C2H3O2) Mg3(PO4)2 Ca(SO4) Mg(OH)2 Na(NO3)

Stock system of nomenclature For transition metals… Some transition metals carry more than one charge Ex: Fe+1, Fe+2, Fe+3…Cu+1, Cu+2 Is depicted with Roman numerals Ex: Fe+2 – Fe(II), Fe+3 – Fe(III) Ex: Cu+2 – Cu(II), Pb+3 – Pb(III) Some metals always have a definite charge Al+3, Zn+2, Ag+1

Stock system of nomenclature For transition metals… Transition metals charge can change so it is always written in the name. Example: Copper (II) Chloride Cu+2 + Cl-1 Cu Cl = CuCl2

Practice with transitions…!! Name the following compounds or give formulas: Copper (II) oxide CuBr2 Tin (IV) iodide FeS Iron (II) chloride Fe2O3

Let’s practice…!! NaI K2O Ca(OH)2 CaCl2 Na(NO3) K2S Ca3(PO4)2 KClO3

Covalent Bonds Nonmetal + Nonmetal Bonds form by SHARING ELECTRONS

Covalent Bonds Electrons are shared from the valence shell, still want it full! But electrons are not always shared equally… When two Chlorine atoms bond, electrons are equally attracted to the positive nucleus of each atom---NON- POLAR Covalent bond When not shared equally-Polar Covalent bond

What makes a Covalent Bond Non-metal + non-metal Some examples below Can share more than one pair of electrons single bond shares one pair electrons double bond shares two pairs electrons triple bond shares three pairs electrons

Naming Covalent Compounds Covalent compounds have different rules than ionic compounds Prefixes are only used for the first atom if it is more than one Second element is named using a prefix to indicate how many Second element’s name ending is changed to “ide” The “a” and “o” at the end of the prefix is dropped when used in the name, followed by a vowel

Naming Covalent Compounds Write the more metallic element first. Add subscripts according to prefixes.

Covalent Bonds Two nonmetal atoms form a covalent bond because they have less energy after they bonded H + H H : H = HH = H2 hydrogen molecule

Diatomic Molecules Gases that exist as diatomic molecules Are: Br2, I2 , N2, Cl2, H2, O2, F2 octets          N  +  N   N:::N   triple bond

Molecular Formulas The Seven Diatomic Elements Br2 I2 N2 Cl2 H2 O2 F2

Learning Check Use the name of the element to name the following diatomic molecules. H2 hydrogen N2 nitrogen Cl2 _______________ O2 _______________ I2 _______________

Solution Use the name of the element to name the following diatomic molecules. H2 hydrogen N2 nitrogen Cl2 chlorine O2 oxygen I2 iodine

Naming Binary Covalent Compounds Two nonmetals Name each element End the last element in -ide Add prefixes to show more than 1 atom (don’t use mono on first element but use all others) Prefixes mon 1 penta 5 di 2 hexa 6 tri 3 tetra 4

Learning Check Fill in the blanks to complete the following names of covalent compounds. CO carbon ______oxide CO2 carbon _______________ PCl3 phosphorus _______chloride CCl4 carbon ________chloride N2O _____nitrogen _____oxide

Solution CO carbon monoxide CO2 carbon dioxide PCl3 phosphorus trichloride CCl4 carbon tetrachloride N2O dinitrogen monoxide

Learning Check A. P2O5 1) phosphorus oxide 2) phosphorus pentoxide 3) diphosphorus pentoxide B. Cl2O7 1) dichlorine heptoxide 2) dichlorine oxide 3) chlorine heptoxide C. Cl2 1) chlorine 2) dichlorine 3) dichloride

Solution A. P2O5 3) diphosphorus pentoxide B. Cl2O7 1) dichlorine heptoxide C. Cl2 1) chlorine

Some examples… Give the name for As2O5 SO3 ICl3 PBr5 Two arsenic atoms as indicated by the subscript – “di” Five oxygen atoms as indicated by the subscript – “penta” Diarsenic pentoxide Notice the oxygen changes to oxide SO3 ICl3 PBr5 Sulfur trioxide Iodine trichloride Phosphorous pentabromide

Try these… CI4 PCl3 N2O3 P2O3 CSe2 S2Cl2 Carbon tetriodide Phosphorous trichloride Dinitrogen trioxide Diphosphorous trioxide Carbon diselinide Disulfur dichloride

Let’s try it backwards… Phosphorus pentabromide Sulfur trioxide Trinitrogen pentachloride PBr5 SO3 N3Cl5

Naming Acids Honors Only

Definition Acid Compound that forms H+ in water. Formula usually begins with ‘H’. Examples: HCl, HNO3, H2SO4

Acid Names

Acid Names HBr H2CO3 -ide  hydrobromic acid H2SO3 -ate  carbonic acid -ite  sulfurous acid

Acid Formulas hydrofluoric acid sulfuric acid nitrous acid -ide  HF -ate  H2SO4 -ite  HNO2