8.2 - Properties of materials Flashcards
How is the periodic table arranged? [1]
In order of atomic number
What is the atomic number of an element? [1]
The number of protons
What is the atomic mass of an element? [1]
The number of protons and neutrons
What is the charge of protons? [1]
+1 / positive
What is the charge on neutrons? [1]
0 / neutral
What is the charge on electrons? [1]
-1 / negative
Why is an atom neutral? [3]
Same number of positive protons and negative electrons
What is the relative mass of protons? [1]
1
What is the relative mass of neutrons? [1]
1
What is the relative mass of electrons? [1]
1/2000
Where are protons found in the atom? [1]
In the nucleus
Where are neutrons found in the atom? [1]
In the nucleus
Where are electrons found in the atom? [1]
In shells / energy levels
What is the maximum number of electrons in the 1st, 2nd and 3rd shells?
1st = 2, 2nd = 8, 3rd = 8
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
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 an ionic bond [2]
The electrostatic attraction between positive metal ions and negative non-metal ions
What type of structure do ionic substances form? [1]
Giant ionic lattice
Describe the properties of ionic substances [4]
Low volatility, high solubility, high melting and boiling point, conducts when molten or aqueous
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
Describe the structure of silicon (IV) oxide [2]
Giant structure, one silicon atom for every two oxygen atoms
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
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
