Year 10 Chemistry

Describe the difference between a decomposition reaction and a combination reaction.

- Decomposition reactions occur when a single reactant breaks down into two or more smaller products. It's general formula is: XY → X + Y - Combination reactions are the other way round: two smaller reactants combine to form a larger product.

State the full subshell configurations for Silicon, Fluorine and Argon.

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Why are metals generally good conductors of electricity?

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a. List 2 examples of reactions at home that you speed up

1) Cooking using heat 2) Mixing ingredients together when baking

b. List 2 examples of reactions at home that you slow down

1) Using large pieces of wood in a fire 2) Decrease the concentration of ingredients

To increase the rate of chemical reactions you can do the following: · increase temperature · increase surface area · agitate the reaction · add a catalyst · increase the concentration of the reactants · Increase the pressure of the reactants. Choose 3 from the list of 6 above, and explain how altering them changes the rate of reaction.

1. We increase the pressure of the reactants, the space between the atoms is smaller. They are more likely to collide. 2. A catalyst is a chemical that speeds up chemical reactions, but does not get used up in the reaction. 3. Finally, if we increase the surface area of solid reactants by crushing them, more atoms will be able to collide.

How many electrons are in an atom with the electron configuration: 2, 8, 8?

18 electrons

If a chemical equation contained the formula 2CH4, what is the meaning of the number 2 and the number 4?

2 = The number at the front of a molecule tells you how many of that molecule there are, and is a multiplier. It applies to all the atoms in the molecule. 4 = A number after an atom only applies to that atom.

How many electrons can an orbital contain?

2 electrons

If Barium forms the cation Ba2+, then how many electrons has it lost or gained?

2 is gained

What is the maximum number of electrons that can fit in each of the first 4 electron shells?

2, 8, 18, 32

Explain what the each of the figures mean in the term 3p5.

3 = shell number p = subshell 5 = how many electrons are in the subshell

How many shells are occupies in atoms of the elements in period 4?

4

What is a precipitate?

A solid

Define Electron Shell

Also known as energy levels; the regions surrounding the nucleus where electrons may be found

What is the law of conservation of mass?

Atoms cannot be created or destroyed

Being in group 16, how many electrons does Selenium need to gain to fulfil the Octet Rule for its valence shell?

Being in group 16, they have 6 valence electrons. If each shares two with its partner, they both have 8 in their valence shell thanks to a double bond forming.

How did Bohr and Schrodinger picture the electron shells in atoms?

Bohr described the shells as fixed 'tracks' along which the hard electrons orbit the nucleus.

Both corrosion and combustion reactions are those that occur between oxygen and a metal. Describe the main difference between these 2 types of reactions.

Combustion is a quick reaction. Corrosion is a slow reaction.

Define Corrosion

Corrosion is where a metal reacts with oxygen in the air to form a metal oxide. The general formula is: Metal + oxygen → metal oxide

List 2 examples of fast reactions and 2 examples of slow reactions.

Fast = Neutralization & Magnesium ribbon is burnt in the flame of Bunsen burner; it quickly gets combusted with a noticeable spark. & photosynthesis Slow = Rusting of iron & formation of coal

What letters are given to the electron subshells and how many orbitals do each contain?

He called the subshells s, p, d and f. s = subshells have 1 orbital. p = subshells have 3. d = subshells have 5. f = subshells have 7. In other words, s subshells can hold 2 electrons, p can hold 6, d can hold 10 and f can hold 14.

What does 'rate of reaction' mean?

How fast a chemical reaction proceeds

Define Endothermic

If a reaction absorbs heat (i.e. it gets cold) it is said to be endothermic.

Define Exothermic

If a reaction produces heat it is said to be exothermic.

Why are ionic lattices brittle when compared to metallic ones?

In an ionic lattice, moving the atoms may result in the protons coming close to each other; this will result in repulsion. This explains why ionic lattices are brittle but metallic ones are not.

Define Respiration

Is a chemical reaction happening in the cells of your body.

Define Combustion

Is any reaction in which a substance burns in oxygen to form light and heat.

Define Electron Configuration

Is how many electrons an atom has, and where they are

State the types of atoms that metallic, covalent and ionic bonding occur between.

Metallic bonding = metals Covalent bonding = non-metals Ionic bonding = metals and non-metals

What would happen when sodium hydroxide reacts with barium acetate?

Precipitation would occur.

What is found on the left side of the → and on the right side of the →?

Reactants are found on the left and products on the right.

What products are formed when an acid and a base neutralise each other?

Salt + water

Are electrons shared or donated in covalent bonding?

Shared Atoms that bond together share their valence electrons, though only in pairs (not a sea, like in metallic bonding).

What charge does a molecule of sodium chloride (NaCl) have? Why?

Sodium chloride contains sodium ions, each with a +1 charge, and chloride ions, each with a -1 charge. Overall, the compound has no charge, because the positive sodiums balance out the charge on the negative chlorides, and vice versa.

Are nitrates normally soluble or insoluble?

Soluble

What is the Octet Rule?

The Octet Rule tells us that atoms are most stable when they have 8 electrons in their valence shell, even if the shell can hold more.

In a chemical equation what does the → symbol mean?

The arrow (→) shows that a reaction has occurred.

Define Ground State

The lowest energy arrangement of an atom's electrons in energy levels (shells).

Why are hydrogen and helium exceptions to the Octet Rule?

The only exceptions to this are hydrogen and helium, whose single shells can only hold 2 electrons.

What is lustre and why are metals lustrous?

When light strikes a metal, the light is reflected and scattered from the electrons, giving metals their characteristic lustre ('shiny-ness').

Describe what the term 'sea of electrons' refers to in metallic bonding.

When metal atoms bond, they are arranged into uniform rows and columns with neighbouring atoms' orbitals overlapping one another. As a result of this, the electrons become delocalised. This results in a 'sea of electrons'.

What is an everyday example of a neutralisation reaction?

Your stomach contains hydrochloric acid, and too much of this causes indigestion. Antacid tablets contain bases such as magnesium hydroxide and magnesium carbonate to neutralise the extra acid.

How many electrons are in the outer shell of atoms in the following groups: a. Group 1 b. Group 13 c. Group V - 5 d. Group VIII - 8

a = 1 electron b = 3 electrons c = 5 electrons d = 8 electrons

Determine the electron configuration of: a. Lithium (3 electrons) b. Carbon (6 electrons) c. Sodium (11 electrons)

a = 2, 1 b = 2, 4 c = 2, 8, 1

Provide one example of a: a. Endothermic reaction: b. Exothermic reaction:

a = A chemical ice pack b = A campfire

List the products formed when: a. An acid reacts with a carbonate b. An acid reacts with a metal

a = Acid + metal → salt + hydrogen b = Acid + carbonate → salt + water + carbon dioxide

Identify which equations are balanced or not: a. 4Al + 3O2 → 2Al2O3 b. Mg + 2HCl → MgCl2 + H2 c. 2Zn + O2 → 2ZnO d. C5H12 + 8O2 → CO2 + 6H2O

a = Balanced b = Balanced c = Balanced d = Unbalanced C5H12 + 8O2 → 5CO2 + 6H2O

Name the following ionic compounds: a) CrF3 b) MgSO4 c) FeN d) Pb3P4.

a = Chromium Fluoride b = Magnesium Sulfate c = Iron nitrate d = Lead Phosphide

Which term best describes: a. Type of chemical reaction where a single reactant forms 2 products b. Something that does not dissolve c. Type of chemical reaction where 2 reactants form one product

a = Decomposition b = insoluble c = Combination

Consider a molecule of copper sulfate: CuSO4. a. Name the atoms found in copper sulfate. b. How many of each atom are there? c. Why would it be incorrect to write copper's symbol as CU instead of Cu? What would CU mean?

a = copper, sulfur, oxygen b = 1 copper, 1 sulfate, 4 oxygen c = Cu means that it's just copper, however if it was CU, then it's implying that that there is an element of 'C' and 'U'.

Write the ionic formulae for the following compounds: a) calcium phosphide b) silver carbide c) zinc nitrite d) ammonium nitrate e) lead (II) nitride.

a) Ca3P2 b) Ag2C2 c) Zn₃N₂ d) NH4NO3 e) Pb(N3)2

What effect would the following changes have on a wood fire heater? a) The wood is chopped into smaller pieces b) The vent is closed so less air can get in. Justify your predictions.

a) If the wood is chopped into smaller pieces than it will increase the surface area, causing more atoms to collide. b) If the vent is closed so less air can get in, then it will add heat energy, which gives the atoms more kinetic energy, so there are more collisions.

1. Determine the period and group of the following Electron Configuration: a = 2, 3 b = 2, 8, 7 c = 2, 8, 8, 2 d = 2, 8, 18, 6 e = 2, 8, 18, 8, 2

a: P = 2 G = 3 b: P = 2 G = 7 c: P = 4 G = 2 d: P = 4 G = 6 e: P = 5 G = 2

Explain what the terms malleable and ductile mean

malleable (able to be hammered or pressed into thin sheets) ductile (able to be drawn into long, thin strands).