The Chemical Earth Flashcards by Andrew Trout

What is a homogenous substance?

A substance that contains evenly spread components.

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What is a heterogenous substance?

A substance that contains unevenly spread components.

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What is a pure substance?

A substance that only contains one compound.

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What is a mixture?

A substance that contains several compounds.

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What is the difference between a compound and an element?

A compound can be decomposed into other substances but an element can not.

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What does filtration separate?

A liquid and an undissolved solid.

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What is sedimentation, and what does it separate?

Waiting for sediment to settle to the bottom of a glass over time.
It separates an undissolved solid and a liquid.

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What does distillation separate?

Liquids with different boiling points.

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What is the difference between evaporation and distillation?

In evaporation, the liquid that evaporates is not collected.

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What is decantation?

Slowly pouring a liquid off the top of a solid.

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What does crystallisation separate?

Components with different solubilities.

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What does centrifugation separate?

Components with different densities or in different states.

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Name a mixture in the biosphere, and state an element and a compound found within it.

Mixture - Soil
Elements - Iron, Oxygen, Nitrogen
Compounds - Water

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Name a mixture in the lithosphere, and state an element and a compound found within it.

Mixture - Rock
Elements - Gold, Silver
Compounds - Ore

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Name a mixture in the hydrosphere, and state an element and a compound found within it.

Mixture - Sea Water
Elements - Oxygen, Nitrogen
Compounds - Water, Sodium Chloride

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Name a mixture in the atmosphere, and state an element and a compound found within it.

Mixture - Air
Elements - Oxygen, Nitrogen, Argon
Compounds - Water, Carbon Dioxide

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What is the relationship between a solute and a solvent?

A solute is dissolved in a solvent in solution.

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When compounds contain oxygen and another element, their suffix changes to what?

‘-ite’ if it is the variant with the least oxygen

‘-ate’ if it is the variant with the most oxygen

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If extra hydrogen is added to a compound, what about its name changes?

‘bi-‘ is added to the second term.

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What is the relationship between the reactivity of an element and how likely it is to be found uncombined in nature.

The less reactive an element the more likely it is that it will be found uncombined in nature.

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What is the name of the following compound?

KHCO3

Potassium Bicarbonate

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Define a physical property and give four examples of physical properties.

A physical property can be examined without a chemical change in the substance.

Eg Boiling Point, Colour, Conductivity, Hardness and Malleability

Define a chemical property and give two examples of chemical properties.

A chemical property requires a chemical change in order to be observed.

Eg Reactivity and Ph

What is a cation?

An ion that has lost electrons to gain a positive charge.

What is an anion?

An ion that has gained electrons to gain a negative charge.

What is the trend in the size of an atom on the periodic table?

The size of an atom increases down and to the left.

What are isotopes?

Atoms with the same number of protons but different numbers of neutrons.

What atomic particles determine an element's physical and chemical properties?

Protons and neutrons

What is a monatomic element? Give two examples.

An element that contains only one atom in its molecule. Eg Iron and Carbon

What is a diatomic element? Give two examples.

An element that contains two atoms in its molecule. Eg Oxygen and Chlorine

Does forming chemical bonds emit or require energy?

Emit energy.

Does breaking chemical bonds emit or require energy?

Require energy.

Describe the molecular structure of a metallic compound.

One type of ion surrounded by a sea of delocalised electrons.

Describe the molecular structure of an ionic compound.

Two types of ions connecting to each other in a lattice.

Describe the molecular structure of a covalent network compound.

A giant lattice of atoms.

Describe the molecular structure of a covalent molecular compound.

Several atoms covalently bonded together.

What is the difference between a small molecule and a big molecule?

Small molecules are limited in size, whereas big molecules are limitless in size.

Describe the melting point and conductivity in solid and liquid state of metallic, ionic, covalent molecular and covalent network compounds.

Group Melting Point Solid Conductivity Liquid Conductivity Metallic High High High Ionic High Low High Cov. Network High Low Low Cov. Molecular Low Low Low

A compound has a low melting point, low solid conductivity and low liquid conductivity. What is most likely its molecular structure?

Covalent molecular.

A compound has a high melting point, low solid conductivity and low liquid conductivity. What is most likely its molecular structure?

Covalent network.

A compound has a high melting point and low solid conductivity but high liquid conductivity. What is most likely its molecular structure?

Ionic.

A compound has a high melting point, high solid conductivity and high liquid conductivity. What is most likely its molecular structure?

Metallic.

What is the difference between the molecular and empirical formula of a molecule?

The molecular formula demonstrates how many atoms there are in one molecule, whereas the empirical formula demonstrates the ratio of atoms in one molecule.

Out of metals, semi-metals and non-metals, which typically have a high melting or boiling point?

Metals and semi-metals.

Out of metals, semi-metals and non-metals, which typically have low conductivity of heat and electricity?

Non-metals and semi-metals

Out of metals, semi-metals and non-metals, which typically have a low melting or boiling point?

Non-metals

Out of metals, semi-metals and non-metals, which typically have high conductivity of heat and electricity?

Metals.

State two everyday examples of decomposition reactions.

Air bags Sodium Azide -> Sodium + Nitrogen Electrolysis Aluminium Oxide -> Aluminium + Oxygen

State two everyday examples of synthesis reactions.

Rust Fe + O2 -> FeO Pollution N + O -> NO + NO2

Explain the hardness and conductivity of metallic molecules.

Very hard, strong electrostatic attraction leads to strong bonds. High conductivity, delocalised electrons allows for easy conductivity.

Explain the hardness and conductivity of ionic molecules.

Hard, ions tightly bound by electrostatic forces. Conductive when molten, mobile ions can easily conduct.

Explain the hardness and conductivity of covalent molecular molecules.

Soft, weak intermolecular forces. Low conductivity, molecules uncharged and electrons shared so they don't easily flow.

Explain the hardness and conductivity of covalent network molecules.

Hard but brittle, strong forces between atoms but distortion breaks covalent bonds. Low conductivity, electrons localised in bonds leading to minimal electron flow.