1 / 24

UNIT : Nomenclature

UNIT : Nomenclature. TOPIC : Covalent and Polyatomic Compounds. Objectives: Lesson 2 of 3 You will learn what a Covalent C ompound is You will learn how to write the formulas and names for Covalent Compounds You will learn and hopefully memorize the most common polyatomic ions

boris
Download Presentation

UNIT : Nomenclature

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. UNIT: Nomenclature TOPIC: Covalent and Polyatomic Compounds Objectives: Lesson 2 of 3 • You will learn what a Covalent Compound is • You will learn how to write the formulas and names for Covalent Compounds • You will learn and hopefully memorize the most common polyatomic ions • You will also learn how to write formulas and names of polyatomic compounds

  2. Quickwrite In 1-2 sentences answer one of the questions below: • Consider the Compound CO2, how is this compound different from NaCl(hint: look at their location on the periodic table)??? • Why do you think we use prefixes such as “tri-” on words like triceratops, tricycle or tripod?

  3. Covalent Compounds • Earlier we learned about Ionic Compounds which form between cations (usually metals) and anions (usually a non-metals) • Covalent Compounds form when two or more non-metal elements share electrons • Recall that Hydrogen is classified as a non-metal on the periodic table • The simplest covalent compound is Hydrogen gas or H2 • Notice, that the electrons are not transferred, BUT, instead, they are shared between the two atoms • As a result, Covalent Compounds DO NOT have charges like Ionic Compounds • Therefore, we use a completely different naming system when writing their chemical formulas and names H2 - Covalent Compound + - + - Cations (usually metals) Anions (usually non-metals)

  4. What is a Covalent Compound? • A compound formed between two non-metals that involves the sharing of electrons • Example: CO, Carbon Monoxide

  5. Naming Covalent Compounds: • When naming covalent compounds there are certain steps you must follow • These steps will help you throughout this unit and the rest of the course: • The first element in the formula is named first, and the full element name is used 2. The 2nd element is named as though it were an anion (add –ide) 3. Prefixes (mono- 1, di- 2, tri- 3) are used to denote the numbers of atoms 4. The prefix mono- is never used for naming the first element

  6. Prefixes PrefixExample

  7. Naming Covalent Compounds: • Write the name for the covalent compound CO -Carbon Monoxide 1. The first element in the formula is named first, and the full element name is used For Example: we just say “Carbon” forCarbon Monoxide 2. The 2nd element is named as though it were an anion For Example: the Oxygen in CO is oxide 3. Prefixes are used to denote the numbers of atoms- For Example: Since there is 1 oxygen atom we would use the prefix mono- for Monoxide 4. The prefix mono- is never used for naming the first element For Example:CO is called Carbon Monoxide NOT MonocarbonMonoxide

  8. Naming Covalent Compounds: • Write the name for the covalent compound SO3SulfurTrioxide 1. The first element in the formula is named first, and the full element name is used For Example: we just say “Sulfur” forSulfurTrioxide 2. The 2nd element is named as though it were an anion For Example: the Oxygen in SO3 is oxide 3. Prefixes are used to denote the numbers of atoms- For Example: Since there are 3 oxygen atoms we would use the prefix tri- for Trioxide 4. The prefix mono- is never used for naming the first element For Example: SO3 is called SulfurTrioxide NOT MonosulfurTrioxide

  9. Naming Covalent Compounds: • Write the name for the covalent compound N2O5- DinitrogenPentaoxide 1. The first element in the formula is named first, and the full element name is used For Example: we just say “Nitrogen” forDinitrogenPentaoxide 2. The 2nd element is named as though it were an anion For Example: the Oxygen in N2O5 is oxide 3. Prefixes are used to denote the numbers of atoms- For Example: there are 5 oxygen atoms so we would use the prefix penta- for Pentaoxide 4. The prefix mono- is never used for naming the first element For Example: Since their are 2 nitrogen atoms, we use the prefix di- for Dinitrogen

  10. What are the Steps for Naming Covalent Compounds? 1. The first element in the formula is named first, and the full element name is used 2. The 2nd element is named as though it were an anion 3. Prefixes are used to denote the numbers of atoms- mono- 1, di- 2, tri- 3, tetra- 4, penta- 5, hexa- 6 4.The prefix mono- is never used for naming the first element

  11. Practice: Write the names for the following compounds below: • SF6 • PCl5 • N2O4 • CCl4 • CO2 • NO2 Answer: Sulfur Hexafluoride Answer: Phosphorous Pentachloride Answer: DinitrogenTetraoxide Answer: Carbon Tetrachloride Answer: Carbon Dioxide Answer: Nitrogen Dioxide

  12. Practice: Write the formulas for the following compounds below: • Dinitrogen Dioxide • Sulfur Trioxide • DiphosphorousPentaoxide • Nitrogen Monoxide • Carbon Tetrafluoride • Silcon Dioxide Answer: N2O2 Answer: SO3 Answer: P2O5 Answer:NO Answer: CF4 Answer: SiO2

  13. Polyatomic Ions • Polyatomic Ions are a group of two or more atoms that have a particular charge to them • An example would include the ammonium ion NH4+1 • It is composed of 1 nitrogen atom and 4 hydrogen atoms which give it a +1charge • These ions are assigned special names that you must memorize! [ ]+

  14. Polyatomic Ions • Common Polyatomic Ions:

  15. What arePolyatomic Ions? • A group of two or more atoms that have a particular charge to them • No naming rules exist, you must memorize their names and charge • Polyatomic Ions you must memorize:

  16. Practice: Write the formula and charge for each polyatomic ion below: • hydroxide • nitrate • phosphate • sulfate Answer: OH- Answer: NO3- Answer: PO4-3 Answer: SO4-2

  17. Ionic Compounds with Polyatomic Ions • Naming ionic compounds that contain polyatomic ions is very similar to naming ionic compounds • For example, the compound NaOHcontains the cation, Sodium (Na+1) and the polyatomic ion hydroxide (OH-1) • Remember, when Ionic compounds come together, their charges must always be neutral or ZERO • Just like ionic compounds, we write the cation first and the anion second; giving us the compound SodiumHydroxide--NaOH

  18. Ionic Compounds with Polyatomic Ions • Let us look at the compound ammonium nitrate NH4NO3(a very explosive chemical) • Ammonium Nitrate is made up of 2 polyatomic ions Ammonium (NH4+) &Nitrate (NO3-) • When two polyatomic ions come together, a neutral compound NH4NO3 forms between them • Notice, the cation is named first, and anion second

  19. Ionic Compounds with Polyatomic Ions • Consider Silver (I) Nitrate: AgNO3 • The Silver(Ag+1) cationcomes first, and the polyatomic anion Nitrate(NO3-1)comes second • Just like in ioniccompounds, the charges need to be neutral • TheSilver cationAg+with a plus one charge is balanced by the negatively charged polyatomic ion NO3-1 with a negative one charge • It is important to realize that because Silver (Ag) is a transition metal it takes on multiple charges, therefore we still use roman numerals to illustrate charge • Therefore we write: Silver (I)Nitrate

  20. Ionic Compounds with Polyatomic Ions • Consider one more compound: Mg(OH)2 • The Mg+2cation comes first, and the negative polyatomic OH-anion comes second • Just like in ioniccompounds, the charges need to be neutral • Mg+2 needs be balanced by 2 negatively charged polyatomic ions OH- • In the case of Mg(OH)2when more than one polyatomic ion exists, we put PARENTHESIS around them • By putting parenthesis around (OH)2 and a subscript of 2, this tells us we have 2 oxygen atoms and 2 hydrogen atoms ()

  21. What are Ionic Compounds with Polyatomic Ions? • Neutrally charged Compounds that contain a polyatomic ion • When more than one polyatomic ion exists in a compound we put parenthesis around them • Ex: Mg(OH)2& AgNO3

  22. Practice: Write the names for the following compounds below: • NaOH • Ba(OH)2 • NH4Cl • AgNO3 • CaCO3 • Mg(NO3)2 Answer: SodiumHydroxide For assistance, look back at the rules for naming Ionic Compounds Answer: BariumHydroxide Answer: Ammonium Chloride Answer: Silver (I) Nitrate Answer: CalciumCarbonate Answer: Magnesium Nitrate

  23. Practice: Write the formulas for the following compounds below: • Calcium Hydroxide • Magnesium Sulfate • Aluminum Phosphate 4) AmmoniumHydroxide 5) Iron (II) Sulfate 6) Calcium Phosphate Answer: Ca(OH)2 For assistance, look back at the rules for naming Ionic Compounds Answer: MgSO4 Answer: AlPO4 Answer: NH4OH Answer: FeSO4 Answer: Ca3(PO4)2

  24. Summarize:(you can always write you own) • Explain the difference between a Ionic Compound and a Covalent Compound: • What numbers do the following prefixes represent: tetra-, tri-, penta- , hexa- • Write down the polyatomic ions you need to memorize, arrange them in order according to their charge: • Explain how we name polyatomic compounds: • Explain how we write formulas for polyatomic compounds: • What do we do if more than one polyatomic ion is present in a compound?

More Related