Topic 1: Key Concepts In Chemistry Flashcards
What is ionic bonding?
When a metal and a non-metal react together, the metal atoms loses electrons to form a positive ion(cation) and the non-metal gains these electrons to form a negative ion(anion)
What are the properties of ionic compounds?
- high melting and boiling points
- don’t conduct electricity unless melted
- many dissolve easily in water-so will carry an electrical current
Why do ionic compounds have high melting and boiling points?
Due to the strong attraction between the ions. It takes a large amount of energy to overcome this attraction
Why don’t ionic compounds conduct electricity unless melted?
Because the ions are fixed in place and can’t move. But when an ionic compound melts, the ions are free to move and will carry an electric current
Why do ionic compounds dissolve easily in water and carry an electrical current?
Because the ions separate and are all free to move, so they’ll carry an electrical current
What structure do ionic compounds have?
Ionic compounds will always have a giant ionic lattice structure. The ions form a closely packed regular lattice. There are very strong electrostatic forces of attraction between oppositely charged ions, in all directions
What is a covalent bond?
A strong bond that forms when a pair of electrons is shared between two atoms
What are simple molecular substances made up of?
They are made up of molecules containing a few atoms joined by covalent bonds
What are the properties of simple molecular substances?
- the atoms with the molecules are held together by very strong covalent bonds-forces of attraction between these molecules=very weak
- melting and boiling points are very low
- most molecular substances are liquid/gases at room temp
- as molecules get bigger, the melting&boiling points increase
- molecular compounds don’t conduct electricity
- some are soluble some aren’t
What are the properties of giant covalent structures?
- all atoms are bonded to each other by strong covalent bonds
- they have very high melting&boiling points
- they generally don’t contain charged particles, so they don’t conduct electricity
- they aren’t soluble in water
What are some examples of carbon-based giant covalent structures?
- diamond
- graphite
- graphene
What are fullerenes?
Fullerenes are molecules of carbon, shaped like closed tubes or hollow balls
What is metallic bonding?
Metallic bonding is the strong electrostatic force of attraction between the metal ions and the delocalised electrons.
What are the physical properties of metals?
- the electrostatic forces between the metal ions and the delocalised sea of electrons are very strong
- mostly high melting points
Advantages of 2D presentations
Simple, show what atoms something contains, shows how atoms are connected
Disadvantages of 2D presentations
Dont show the shape of substance or size of atoms
Advantages of dot and cross diagrams
Show how compounds/molecules are formed and where the electrons came from
Disadvantages of Dot and cross diagrams
Dont show size of atoms or how they’re arranged
Advanatges of 3D models
Show arrangement of ions
Disadvantages of 3D models
Only show outer layer of substance
Advanatges of ball and stick model
Helps visualise structures in 3D, more realistic than 2D
Disadvantages of ball and stick models
Misleading, looks like big gaos between atoms, actually where electrom clouds interact and dont show correct scales of atoms/ions
What is an ionic bond
When a metal and non metal react together, the metal atom loses electrons to form a cation(+) and non metal gains these electrons to form a anion(-) . These oppositely charged ions are strong attracted by electrostatic forces
What are ions
Charged particles can be single atoms or groups