C3 - Atoms, elements and compounds Flashcards
Define an element [1]
Made of one type of atom
Define a compound [1]
Made of more than one type of atom chemically bonded together
Describe general physical properties of metals [4]
High melting and boiling points, mallleable, ductile, good conductors of heat and electricity
Define a mixture [1]
Two or more elements / compounds mixed together that can be separated by physical means
What is the difference between a physical change and chemical change? [2]
Physical changes involve a change in state / separation of a mixture. Chemical changes involve atleast one new substance being made
What does the symbol ⇌ mean? [1]
Reversible reaction
What is the difference in colour between the anhydrous and hydrated forms of copper (II) sulphate? [2]
Anhydrous copper sulphate = white, hydrated copper sulphate = blue
What is the difference in colour between the anhydrous and hydrated forms of cobalt (II) chloride? [2]
Anhydrous cobalt chloride = blue, hydrated cobalt chloride = pink
Describe the structure of an atom [2]
Central nucleus containing protons and neutrons, ‘shells’ of electrons
Describe the relative charge and mass of protons [2]
Relative charge = +1, relative mass = 1
Describe the relative charge and mass of neutrons [2]
Relative charge = 0, relative mass = 1
Describe the relative charge and mass of electrons [2]
Relative charge = -1, relative mass = 1/2000
Describe the maximum number of electrons that can fit on the first 3 shells [1]
1st shell = 2 electrons, 2nd shell = 8 electrons, 3rd shell = 8 electrons
Why are elements in group 0 (the noble gases) unreactive? [1]
They have a full outer shell of electrons
How is group number in the periodic table related to electronic structure? [1]
The group number = the number of electrons in the outer shell
How is period (row) number in the periodic table related to electronic structure? [1]
The row number = the number of occupied electron shells
What is the atomic number of an element? [1]
The number of protons in an atom
What is the mass number or an element? [1]
The number of nucleons (protons + neutrons) in an atom
How are elements arranged in the periodic table? [2]
In ascending atomic number, elements with similar properties arranged in groups
Define an isotope [2]
Atoms of the same element with the same number of protons and electrons but a different number of neutrons
Why do isotopes have the same chemical properties? [1]
Because they have the same number of electrons in their outer shell
Describe how metal atoms form ions [2]
Metals lose electrons to form positive ions
Describe how non-metal atoms form ions [2]
Non-metals gain electrons to form negative ions
Describe a ionic bond [2]
The electrostatic attraction between positive metal ions and negative non-metal ions
Describe the properties of ionic substances [4]
Low volatility, high solubility, high melting and boiling point, conducts when molten or aqueous
What type of structure do ionic substances form? [1]
Giant ionic lattice
Explain the high melting / boiling point of ionic substances [2]
High melting point because of strong electrostatic force of attraction between ions that requires a lot of energy to overcome
Explain the electrical conductivity of ionic substances [2]
Able to conduct when molten or aqueous because the ions are free to move and carry charge
Describe a covalent bond [1]
A shared pair of electrons between non-metal atoms
Describe the properties of covalent substances [4]
High volatility, low solubility, low melting and boiling point, does not conduct electricity
Explain the low melting / boiling point of covalent substances [2]
Weak intermolecular forces that require a small amount of energy to overcome
Explain why simple covalent substances don’t conduct electricity [2]
No free mobile charge carriers (electrons or ions) to carry charge through the structure
Name three (covalent) macromolecules [3]
Diamond, graphite, silicon (IV) oxide (silica / silicon dioxide)
Describe the structure of diamond [3]
Giant structure, made of carbon atoms, each carbon forms 4 bonds with another carbon
Describe the structure of graphite [4]
Giant structure, made of carbon atoms, each carbon forms 3 bonds with another carbon, layered structure
Explain why diamond, graphite and silica have a high melting / boiling point [2]
Lots of strong covalent bonds that require a lot of energy to overcome
Describe the structure of silicon (IV) oxide [2]
Giant structure, one silicon atom for every two oxygen atoms
Explain why graphite is able to conduct electricity [3]
Carbon atoms only form 3 bonds so one valence electron is free and delocalised and can carry charge through the structure
Explain why graphite is slippery [2]
Weak intermolecular forces between layers so the layers can slide off each other
What is graphite used for? [2]
A lubricant and a conductor
What is diamond used for? [1]
Cutting tools
