What are the distinguishing properties of solids, liquids, and gases?
- Solids: definite shape and volume
- Liquids: definite volume, takes shape of container
- Gases: neither definite shape nor volume
These properties are based on particle arrangement and motion.
Describe the structure of solids, liquids, and gases in terms of particle separation, arrangement, and motion.
- Solids: closely packed, fixed arrangement, limited motion
- Liquids: close together, random arrangement, moderate motion
- Gases: far apart, random arrangement, high motion
The arrangement and motion of particles determine the state of matter.
Describe changes of state in terms of melting, boiling, evaporating, freezing, and condensing.
- Melting: solid to liquid
- Boiling: liquid to gas
- Evaporating: liquid to gas (at surface)
- Freezing: liquid to solid
- Condensing: gas to liquid
These processes involve energy changes and particle movement.
Describe the structure of the atom.
- Central nucleus containing neutrons and protons
- Electrons in shells surrounding the nucleus
The nucleus is positively charged due to protons.
State the relative charges and relative masses of a proton, a neutron, and an electron.
- Proton: charge +1, mass 1
- Neutron: charge 0, mass 1
- Electron: charge -1, mass ~0
Electrons have negligible mass compared to protons and neutrons.
Define proton number/atomic number.
Number of protons in the nucleus of an atom
This number determines the element’s identity.
Define mass number/nucleon number.
Total number of protons and neutrons in the nucleus of an atom
It indicates the total mass of the atom.
Describe the formation of positive ions and negative ions.
- Positive ions (cations): formed by losing electrons
- Negative ions (anions): formed by gaining electrons
This process involves the transfer of electrons between atoms.
What is an ionic bond?
Strong electrostatic attraction between oppositely charged ions
Ionic bonds typically form between metals and nonmetals.
Describe the formation of ionic bonds between elements from Group I and Group VII.
Involves transfer of electrons, resulting in cations and anions
Dot-and-cross diagrams can illustrate this electron transfer.
What is a covalent bond?
Formed when a pair of electrons is shared between two atoms
This leads to noble gas electronic configurations.
Describe the formation of covalent bonds in simple molecules.
Involves sharing electrons, leading to stable electronic configurations
Dot-and-cross diagrams can be used to show these configurations.
Describe the giant covalent structures of graphite and diamond.
- Graphite: layers of carbon atoms, good conductor of electricity
- Diamond: tetrahedral structure, very hard
Their structures relate to their physical properties and uses.
What are the uses of graphite and diamond?
- Graphite: lubricant, electrode
- Diamond: cutting tools
Their unique structures contribute to these applications.
Describe the giant covalent structure of silicon(IV) oxide, SiO2.
Network of silicon and oxygen atoms bonded covalently
This structure contributes to its hardness and high melting point.
What is the similarity in properties between diamond and silicon(IV) oxide?
Both are hard and have high melting points
Their giant covalent structures account for these similarities.
Describe metallic bonding.
Electrostatic attraction between positive ions in a giant metallic lattice and a ‘sea’ of delocalised electrons
This bonding explains many properties of metals.
Explain the property of good electrical conductivity in metals.
Due to the presence of delocalised electrons that can move freely
This allows metals to conduct electricity efficiently.
Explain the properties of malleability and ductility in metals.
Metals can be shaped and drawn into wires due to layers of atoms sliding over each other
This is a result of metallic bonding.
