Unit 4: atomic structure

Question 1

What’s a synthesis?

Answer 1

A + B –> AB

Question 2

What’s a decomposition?

Answer 2

AB –> A + B

Question 3

What’s a single replacement?

Answer 3

AB + C –> A + CB

Question 4

What’s a double replacement?

Answer 4

AB + CD –> AD + BC

Question 5

What’s a precipitation?

Answer 5

AB(aq) + CD(aq) –> AD(s) + CB(aq)

• Soluble reactants produce in an insoluble solid (precipitate)

Question 6

What’s a combustion?

Answer 6

CnHn(aq) + H2(g) –> CO2(g) + H2O(g)

Question 7

What’s oxidation-reduction reaction?

Answer 7

One or more electrons are transferred between reactants.
- Something solid at first with no charges transforms in an ionic molecule

Question 8

What’s a neutralization reaction?

Answer 8

Acid and base react and form water and salt (ionic compound). The other product is water!
*Acid starts with H
*Base finishes with OH

Question 9

Solute, solvent, solution?

Answer 9

• Solute is the powder that is dissolved
• Solvent is the dissolving medium. WATER IS THE UNIVERSAL SOLVENT.
• Aqueous solution is produced (aq).

Question 10

Why is water the universal solvent?

Answer 10

• Polar covalent molecule
• Water can dissolve polar and ionic solutes!
• Some parts of the water are positive and other are negative.

Question 11

What are more electronegative, metals or non-metals?

Answer 11

Non-metals, because they want to get electrons to have their shell full!
On the other hand, metals DON’T want the electron, they want to give it!

Question 12

Ionic solutes?

Answer 12

• Solute ionic compounds are packed closely together, because of strong ionic forces and form structures called crystal lattices.
• Polar water molecules interact with the positive and negative ions of salt.

Question 13

Polar covalent solutes?

Answer 13

• Polar covalent substances can also dissolve in water!

Question 14

3 different types of equations?

Answer 14

1- Molecular equation: complete, balanced, neutral formulas of all species.

2- Ionic equation: ionic species are shown as ions.

3- Net ionic equation: equation without spectator ions that appear on both sides of the equation.

Question 15

How to know the states in precipitation reactions?

Answer 15

• First balance equation and than write the products while looking at the positive and negative charges.
• Look at the solubility guidelines for ionic compounds in water in order to now if state stays aqueous or becomes solid.

Question 16

What is M?

Answer 16

M = Molarity, which is the number of moles of solute per volume of solution in liters.

M - moles of solute/liters of solution

Question 17

Concentration of ions?

Answer 17

• Ionic coumpouds separate into component ions when they dissolve in water!
• To find de concentration, you multiply the coefficient of the ion times the initial concentration

Question 18

The 2 reactions occuring during a redox reaction?

Answer 18

• Oxidation: loss of one or more electrons
• Reduction: gain of one of more electrons

Question 19

Acronyms to retain redox?

Answer 19

• LEO (Lose electron = oxidized)
• GER (gain electron = reduced)

Question 20

Hal-cell reaction?

Answer 20

• It’s either an oxidation, or reduction, component of a redox reaction.
• Reduction half-cell reaction = gain
• Oxidation half-celle reaction = lost

Question 21

Ionic vs covalent substances?

Answer 21

• Ionic: electrons are transferred and ions are formed
• Covalent: electrons are transferred, but ions are not formed

Question 22

The 6 rules to assigning oxidation numbers?

Answer 22

1) ELEMENTS: oxidation number is always 0 for atoms in elemental state. (ex: K(s) = 0)

2) MONATOMIC ION: oxidation number = it’s charge. (ex: Fe2+ = +2)
*Halogens are usually -1, but if with oxygen, the oxidation number has to be calculated.

3) OXYGEN: Has oxidation number of -2, except peroxides that are -1.

4) NEUTRAL MOLECULE: Sum of the oxidation numbers equals 0 (it’s neutral)

5) POLYATOMIC IONS: Sum of xidation numbers equals charge of ions. (ex: NH4+ = +1)

6) HYDROGEN: oxidation number is +1 or -1

Question 23

The oxidizing agent?

Answer 23

• It’s the substance that has been reduced that causes the oxidation of the other substance.

Question 24

The reducing agent?

Answer 24

• It’s the substance that is oxidized that causes the reduction of the other substance.