Bonding, structure and properties of Matter Flashcards
What type of ions do elements from the groups: 1 and 7 make?
Group 1: they lose electrons to form positive ions (cations)
Group 7:They gain electrons to form negative ions (anions)
Describe how an ionic bond forms
When a metal and non metal react together the metal atoms loses electrons to form a positively charged ion and the non metal gains these electrons to form a negatively charged ions. The opposite charge ions are strongly attracted to another by electrostatic forces.
Describe the structure of a crystal of sodium chloride
Sodium chloride exits of a positive sodium ion and a negative chloride ion which are strongly attracted to each other.
List the main properties of ionic compounds
High melting and boiling points due to many strong bonds between ions
When solid the ions are held in place so it doesnt conduct electricity
When they melt ions are free to move and can carry electric current
Some dissolve in water where the ions separate and are free to move also able to carry current
Describe how covalent bonds form
When non metal atoms bond together they share pairs of electrons to make covalent bonds. They positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces making covalent bonds very strong.
Explain why simple molecular compounds typically have low melting and boiling points
Simple molecular compounds have strong covalent bonds, however they have weak intermolecular forces which is required to break to melt or boil them. This means molecules are easily parted with little energy required. As molecules get bigger the strength of intermolecular force increases.
Describe the structure of a polymer
Polymers are made up of small units linked together to form a long molecule that has repeating sections. All atoms in a polymer are joined by strong covalent bonds.
Give three examples of giant covalent substances
Diamond, graphite and silicon dioxide
Explain why graphite can conduct electricity
Only three out of each carbon’s four outer electrons are used in bonds so each carbon has one electron that’s delocalised therefore it can conduct electricity and thermal energy
Explain how fullerenes and could be used to deliver drugs into the body
Fullerenes are molecules of carbon shaped like closed tubes or hollow balls. Made up of carbon atoms in hexagons, pentagons or heptagons. They can be used to “cage” molecules allowing it to deliver a drug into the body.
Explain why giant covalent structures have high melting and boiling points
In giant covalent structures ALL the atoms are bonded to each other by strong covalent bonds Therefore to melt these structures you will need to break the covalent bonds which requires a lot of energy
What is metallic bonding
The electrons in the outer shell of the metal atoms are delocalised and create strong forces of electrostatic attraction between the positive metal ions and the share negative electrons. These forces hold the atoms in a regular structure and are known as metallic bonding
List three properties of metals and explain how metallic structure causes each property
Solid at room temperature and high melting and boiling points-Electrostatic forces between the metal atoms and delocalised electrons are very strong requiring a lot of energy to be broken
Good conductors-The delocalised electrons carry electrical current and thermal energy through the structure
Malleable-The layers of atoms in a metal can slide over each other making metals malleable.
Explain why alloys are harder than pure metals
An alloy is a mixture of two or more metals or a metal and another elements. Elements have different sized atoms therefore another elements will disrupt the layers of the metal atoms making it difficult for them to slide over each other.
Name the three states of matter
Solids
Liquids
Gases
