Presentation on theme: "Identify the elements present in each of the following compounds and the number of each element atom present. Common salt: NaCl Nitric acid:"— Presentation transcript:
1 Identify the elements present in each of the following compounds and the number of each element atom present.Common salt: NaClNitric acid: HNO3Carbon dioxide: CO2Sodium Hydroxide: NaOHSodium carbonate: Na2CO3Copper sulfate: CuSO4Sodium bicarbonate: NaHCO3Ammonium sulfate: (NH4)2SO4Potassium permanganate: KMnO4Sodium thiosulfate: Na2S2O3Calcium bicarbonate: Ca(HCO3)2Calcium Nitrate: Ca(NO3)2
3 Properties of Ionic Compounds They have high melting and boiling pointsThey are hard and brittleThey do not conduct electricity in the solid stateWill conduct electricity when in solution (dissolved in water) or molten (liquid state)Will often dissolve in water to form ions
4 Ions – Charged atoms or molecules An ion is an atom or molecule which has lost or gained one or more electrons, making it positively or negatively charged.Anions are negatively charged ions because they have more electrons in its electron shells than it has protons in its nuclei. They gain electrons e.g. Cl atom Cl-Cations are positively charged ions because they have more protons than electrons. Cations lose electrons e.g. sodium Na+The number of electrons an atom gains or loses is called its valencyCations and anions only form when cations transfer their outershell electrons to the anions
7 Getting stable – Bonding The noble gases have a full outer shell and are very unreactive or stableAtoms are most stable when their outer shell is full like the noble gasesHow do you get a full outer shell? gain or lose or share electrons when forming compounds and moleculesA covalent bond is formed when electrons are shared between atoms.An ionic bond is formed when electrons are transferred from one atom to the other
8 Ionic BondingWhere does the Chlorine ion get that extra electron from?From Sodium who wants to give one away!In ionic bonding, electrons are completely transferred from one atom to another.It happens between a metal and a non metal Why?Because metals form positive ions (cations) and non metals form negative ions (anions)The oppositely charged ions are attracted to each other by electrostatic forces
9 During a reaction of sodium with chlorine, sodium loses its one valence electron to chlorine.
10 Resulting in a positively charged sodium ion and negatively charged chlorine ion.
11 Some important things to know Where do you find the charges for ions? Look at your valency table?Subscript is set below a word HelloYr 11Superscript is set above the Hello Yr 11
12 Rules for writing chemical formulas Write the symbols and charge for ions involved. Write charge as superscript.Determine the subscripts that will produce no chargeCheck that the total positive charge and negative charge equal 0Write final chemical formula without the charges just subscriptsMg2+ Cl-Mg Cl-= 0MgCl2
13 Polyatomic Ions Na+ SO42- Al3+ SO42- 2 Na+ SO42- 2 Al3+ 3SO42- For polyatomic ions you cannot change the formula of the ion.For polyatomic ions if there is more than one of them you must put them in brackets and place the subscript outsideNa+ SO Al SO42-2 Na+ SO Al3+ 3SO42-= = 0Na2 SO Al2(SO4)3
14 Fill in the table Iodide I- Oxide O2- Copper Cu2+ Potassium K+ Aluminium Al3+
15 Form an ionic bond between the following Na and ClCl and FNa and MgMg and BrNH4+ OH-NH4+ SO42-
16 Naming Ionic Compounds 1. Name the positive ion first by writing full name of metalFor metals that can have more than one charge (valency) the name of the metal is followed by the valency in capital Roman numerals in brackets e.g. Iron(II) Chloride2. Name the anion second.Negatively charged elements have the suffix or ending -ide Examples are oxide (O2-), sulfide (S2-), fluoride (F-), chloride (Cl-), bromide (Br-), iodide (I-), nitride (N3-), hydride (H-)
17 Naming Ionic Compounds 3. Polyatomic ions which include oxygen in the anion have the suffixes -ate or -ite."ate" means there is more oxygen in the anion than one ending in "ite"Examples: sulfate (SO42-) has more oxygen than sulfite (SO32-), nitrate (NO3-) has more oxygen in the anion than nitrite (NO2-)Other examples are carbonate (CO32-), phosphate (PO43-) and permanganate (MnO4-) Exception: OH- is named hydroxide
18 Fill in the names of the following compounds Iodide I-Oxide O2-Copper Cu2+Copper (II) IodidePotassium K+Aluminium Al3+
19 The ionic bonding model Positive metal ions (cations) and negative non metal ions (anions) are arranged in a regular arrangement, called a latticeThe 3D lattice is held together strongly by electrostatic forcesElectrostatic forces are the forces between particles that are caused by their electric charges
20 Explaining properties of ionic compounds Why do ionic compounds have relatively high melting points?Remember the melting point of a compound is when it goes from being a solid to a liquidThe bond between the cations and anions are very strong and hence a large amount of energy is required to separate the bonds.
21 Why are ionic compounds brittle? When an external force distorts the crystal this causes ions of like charge (e.g. ++) to come close together (align) and the repulsion between these ions shatters the crystal.Why are ionic compounds hard?The bonds between the cations and anions are very strong.
22 Why do ionic compounds conduct electricity when in solution or molten? When molten (liquid) ions are able to slide past each other. While in solution (meaning in water) ions dissociate (move out) from the lattice and can move freely so are able to conduct electricityWhy do ionic compounds not conduct electricity when solid?When solid, the ions are notable to move.
23 Why do ionic compounds dissolve in water? Water molecules are able to move between ions and free them by disrupting the rigid crystal structure
24 Uses of Ionic compounds Read the pages 103 – 104 and summarizeYr 11 Camp Homework Due Date: Wednesday Week 3Complete Ionic compound sheets.Add words to the glossary at the back of your workbook (look at pg 51, 70, 90 and 107 of your Chemistry textbook at key terms).Read Chapter 7: Covalent molecules, networks and layers (pages 110 – 131).