Access to HE Diploma Pharmacy and Biomedical Science Introduction to Matter Lesson 6

Hand in homework Moles, Formulae and Equations workbook.

Assessment Criteria 1.1 Define an element giving examples. 1.2 Write the names and symbols of the first 20 elements. 1.3 Describe and explain what some of the general physical properties of metals and non-metals are 1.4 Describe the relative position of metals, non-metals, groups and periods within the periodic table with examples.   2.1 Classify substances as elements or compounds from their names giving examples 2.2 Describe two differences between a compound and a mixture 3.1 Describe protons, neutrons and electrons in terms of their relative charges and relative masses. 3.2 Describe the distribution of mass and charge within an atom. 3.3 Describe the contribution of protons and neutrons to atomic nuclei in terms of atomic number and mass number. 3.4 Deduce the electronic configurations of atoms up to z = 36 and ions, given the atomic number and charge, limited to s and p blocks up to Z= 36. 4.1 Describe ionic bonding as the electrostatic attraction between two oppositely charged ions including dot and cross diagrams. 4.2 Describe a covalent bond as a pair of electrons shared between two atoms 4.3 Write the formulae for some simple and some complex compounds 4.4 Describe and interpret and/or predict physical properties in terms of the types motion and arrangement of particles (atoms, molecules and ions) and the forces between them, and the different types of bonding. 5.1 Describe an acid as a species that can donate a proton. 5.2 Describe a base as a species that can accept a proton 5.3 Describe the reaction of an acid typified by hydrochloric acid with metals, carbonates bases and alkalis and interpret them using ionic equations to emphasise the role of H+(aq) 5.4 Write a balanced equation for the reaction between two elements and between an acid and a base 6.1 Construct balanced chemical equations, full and ionic

Review Activity acid + metal carbonate →

Review Activity Write a balanced equation for the reaction between two elements Write a balanced equation for the reaction between an acid and a base

Today’s Aim Understand that chemical reactions can be represented by chemical equations

Week 6 6.1 Construct balanced chemical equations, full and ionic

Week 6 Reading Access to Chemistry Alan Jones, Mike Clement, Avril Higton Elaine Goulding ISBN 0 -85404-564-3 Inside the atom Pages 83 - 118

What happens when you put AgNO3 (aq) + NaCl(aq) AgCl(s) + NaNO3(aq) What happens when you put AgNO3 and NaCl in water?

What really happens when you put AgNO3 (aq) + NaCl(aq) AgCl(s) + NaNO3(aq) What really happens when you put AgNO3 and NaCl in water?

NaCl (aq) Na +1 (aq) + Cl -1 (aq) KEY POINT: really means: “dissociated ions” or “ions in solution”

What is Dissolving ? When an ionic compound (eg salt) dissolves in water, the compound disassociates. (breaks apart into cations and anions) Ex: Ca(NO3)2(s) Ca2+(aq) + 2NO3-(aq) When a covalent compound (eg sugar) dissolves in water, the molecules simply disperse; they do not disassociate. Molecules of the covalent compounds simply disperse due to attraction with polar water molecules.

An Ionic Compound Dissolves: A Covalent Compound Dissolves:

Mg(NO3)2 (aq) Mg +2 (aq) + (NO3) -1 (aq) 2 KEY POINT: really means: “dissociated ions” or “ions in solution”

KEY POINT: AgCl (s) really means: Solid Silver (I) Chloride.

What happens when you put AgNO3 (aq) + NaCl(aq) AgCl(s) + NaNO3(aq) What happens when you put AgNO3 and NaCl in water?

AgNO3 NaCl

NO3- Na+ Ag+ Cl-

Na+ NO3- Ag+ Cl-

Na+ NO3- AgCl

Na+ NO3- AgCl(s) precipitate AgCl

AgCl(s) NO3- Na+ NO3- NO3- Na+ Na+ Na+ NO3- NO3- Na+ Na+ Na+ NO3- NO3-

AgNO3 (aq) + NaCl(aq) AgCl(s) + NaNO3(aq) complete ionic equation

Na+ NO3- AgCl Reaction

No Reaction Na+ NO3- AgCl

These ions do not participate in the reaction. They are called SPECTATOR IONS Na+ NO3- AgCl

The net ionic equation is constructed from the complete ionic equation:

NO3- and Na+ are not participating in the reaction

net ionic equation

net ionic equation

describes double replacement reaction Complete molecular equation- describes double replacement reaction Complete ionic equation- more accurately shows the reacting species as ions and the products either as ions or a precipitate Net ionic equation- focuses only on the ions REACTING Spectator ions are those ions that do NOT participate in the reaction

PREDICTING THE FORMATION OF A PRECIPITATE Consider the possibility that a precipitate may form. Must use the solubility table. Possible outcomes No visible reaction (nvr) Formation of one ppt. Formation of two ppt. (rare occurrence)

Basic Chemical equation AgNO3(aq) + KCl(aq) AgCl(s) + KNO3(aq) Complete ionic equation shows ions in solution Ag+ (aq) + NO3(aq) + K+ (aq) + Cl-(aq)  AgCl(s) + K+ (aq) + NO3- (aq) Net ionic equation shows ions in rxn Ag+ (aq) + Cl-(aq)  AgCl(s) (leave out spectator ions) link

Review Week 6 6.1 Construct balanced chemical equations, full and ionic

Workbook Complete section

Next Week Exam