Chemistry subtopic 3: R2.1 and S2.1 and Titration

process for when an ionic compound dissolves and the ions become surrounded by water molecules.

hydration

m

n

Covalent bond

A covalent bond is formed by the electrostatic attraction between a shared pair of electrons and the positively charged nuclei.

Metallic bond

a bond formed between metal atoms due to the attraction of free-floating electrons to positively charged metal ions, allowing for conductivity and malleability.

Hydrogen bond

Hydrogen from a molecule attracts an electronegative atom from another molecule electrostatically

Polyatomic ions

ions composed of more than one atom

m

• n

Spectator ion

Found on both sides

Complete ionic equation

write as dissociated uibs (get rid of ionic bonds but leave covalent etc)

Net ionic equation

cancel out spectator ion on both sides

Limiting reactant

The substance which is completely consumed in a chemical reaction and determines the yield of the product formed

Excess reactant

The reactant which is still remaining after the reaction has taken place.

Metal physical state and exception

solid, Hg (l)

Non metals physical state and exception

Gases, C (s), S8(s), Br2 (l), I2 (s), P4(s), Clever Students Bring Ice Pops

Ionic compounds eg and physical state

NaCl, CaCO3, solids at room temperature, many dissolve in H20

Molecular compounds

CO2

STP

0 degrees, 273.15K, 100kPa

SAmbientTP

25 degrees, 100kPa

Reasons for lower experimental yield (4)

• loss of product - evaporation and spillage

• Incomplete reaction - impurities and not enough time

• Side/Alternative reactions

• Impure reactants

Reasons for greater experimental yield

• Presence of moisture

• Precipitate not dry

Precipitate

insoluble solid from a reaction in solution

Atom economy

Measure of reaction efficiency, compares to total mass of reactant atoms which end up as desired products

Titration

a technique used to determine the unknown concentration of a solution by reacting with solution of known concentrtion

Équivalence point

point at which reaction is complete

indicator

substance that changes colour at end point

ionic bond

electrostatic attraction between oppositely charged ions that holds its electrons in close proximatey

lattice

a 3D regular repeating arrangement of ions, atoms or molecules in a crystalline solid

Latice enthalpy IB def

endothermic process of turning a crystalline solid into its gaseous ions

Volatility

the ease at which a substance vaporizes or becomes a gas

what causes increasing ionic bond strength (3)

• As the radius of the cation increases (bcs more energy levels are occupied), the lattice enthalpy decreases

• the greater distance between two ions as radius increases, weakening electrostatic attraction

• Group 2 chlorides have a higher lattice enthalpy then G1 and so on, bcs the greater distance between two ions as radius increases so electro static attraction is weakened

Physical properties of ionic compounds (6) and why see nb2

• high melting/boiling pts

• low volatility

• many but not all are water soluble

• not electrically conductive as a solid, only when dissolved in water or molten liquid

• brittle

• hard

Hydroxide ion

OH-

Phosphate ion

PO4 ,3-

Sulphate ion

SO4, 2-

Carbonate ion

CO3, 2-

Hydrogen carbonate ion

HCO3, -

Nitrate ion

NO3 -

Ammoniumm ion

NH4+

ionic bond

a type of chemical bond that involves the electrostatic attraction between two oppositely charged ions,