C3 - Atoms, elements and compounds Flashcards
Define an element [2]
- Made of a single type of atom
- Cannot be broken down into smaller parts
Define a compound [1]
- Made of more than one type of atom chemically bonded together
Define a mixture [2]
- Two or more elements or compounds mixed together
- Can be separated by physical means
Describe properties of metals [8]
- Usually solids at room temperature
- Malleable
- Ductile
- Shiny
- High melting and boiling points
- High density
- High electrical conductivity
- High thermal conductivity
What is the difference between a physical and a chemical change? [3]
Physical changes can involve;
- Change of state
- Separation of a mixture
Chemical changes involve;
- At least one new substance being made
What does ⇌ mean? [1]
- Reversible reaction
What is the difference in colour between the anhydrous and hydrated forms of copper (II) sulphate? [2]
- Anhydrous: white
- Hydrated: blue
What is the difference in colour between the anhydrous and hydrated forms of cobalt (II) chloride? [2]
- Anhydrous: blue
- Hydrated: pink
Describe the structure of an atom [2]
- Central nucleus containing protons and neutrons
- Surrounding ‘shells’ of electrons
Describe the relative mass and charge of following; protons, neutrons and electrons [6]
Protons:
- 1
- (+1)
Neutrons:
- 1
- (+-0)
Electrons
- 0 (1 over 2000)
- (-0)
Describe the configuration of the inner three shells of an electron [4]
- Innermost shell: 2 electrons
- Second shell: 8 electrons
- Third shell: 8 electrons
- Total: 18 electrons
Why are the elements in group 0 (the noble gases) unreactive? [1]
- Because they have full outer shells of electrons
How is group number on the periodic table related to electronic structure? [1]
- Group number = number of valance electrons
How is period number on the periodic table related to electronic structure? [1]
- Period number = 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 of an element? [1]
- The number of nucleons (protons + neutrons) in an atom
How are the elements arranged in the periodic table? [2]
- In ascending atomic number
- Elements with similar properties arranged in groups
Define isotope [2]
- An atom of the same element but with a different number of neutrons
+ Changes atomic mass
Why do isotopes have the same chemical properties? [1]
- Because they have the same number of valance electrons
Describe how metal atoms form ions [1]
- Metals lose electrons to form positive ions
Describe how non-metal atoms form ions [1]
- Non-metals gain electrons to form negative ions
Describe an ionic bond [1]
- The electrostatic force of attraction between positive metal ions and negative non-metal ions
What type of structure does ionic substances form? [1]
- Giant ionic lattice
Describe the properties of ionic substances [4]
- Low volatility
- High solubility
- High melting and boiling point
- Conducts electricity when molten or aqueous
