C3 Flashcards
particles in a solid
packed closely together and vibrate around fixed positions. cannot be compressed
particles in a liquid
close together but can slip over each other in random motion.
particles in a gas
lots of space between them and move around randomly
melting and boiling
energy is transferred from the surroundings to the substance
freezing and condensing
energy is transferred from the substance to the surroundings
particle model
The simple particle model is useful when comparing properties, but has limitations because the atoms, molecules and ions that make up substances are not solid spheres with no force between them.
forming compounds
elements react together to form compounds by gaining or losing electrons
losing electrons to form positive ions
In ionic bonding atoms lose or gain electrons to form charged particles called ions
gaining electrons to form negative ions
when non metals react with metals, the non metal atoms gain electrons to achieve the stable electronic structure of a noble gas.
representing ionic bonding
metal atoms that lose electrons react with non metal atoms which tend to gain electrons
ionic bonding
Ionic compounds are held together by very string forces of attraction between their oppositely charged ions. This is called ionic bonding
The ionic bonds between the charged particles result in an arrangement of ions called a giant structure or giant lattice.
giant ionic lattice
- It takes a lot of energy to break the many strong ionic bonds, operating in all different directions, that hold a giant ionic lattice together.
- Ionic compounds have high m.p
- all solids at room temp
do ionic compounds conduct electricity?
- ionic compounds conduct electricity when molten or dissolved in water, because their ions become mobile and carry charge
covalent bonding
- covalent bonds are formed when atoms of non-metals share pairs of electrons with each other
- The atoms of non-metals tend to gain electrons to get stable electron structures
- Each shared pair of electrons is a covalent bond
simple molecules
- substances made of simple molecules have low m.p and b.p
- forces between simple molecules are weak, which is why they have low m.p and b.p
- they have no overall charge, so they cant carry electrical charge and dont conduct electricity