Topic 2- Bonding, Structure and Properties of Matter.

Question 1

when are ions made?

Answer 1

when electrons are transferred.

Question 2

formation of ions?

Answer 2

• ions = charged particles.
• formed when atoms gain or lose electrons - get a full outer shell.
• metal atom lose electrons from their outer shell to form positive ions.
• non-metal atoms gain electrons into their outer shell to form negative ions.
• the number of electrons lost or gained is the same as the charge on the ion.
• 2 electrons lost = has two more protons than electrons so the charge is 2+.
• 3 electrons gained = has three more electrons than protons so the charge is 3-.

Question 3

what ions can you work out?

Answer 3

when ions are formed by groups 1&2 and 6&7.

• group 1=form ions by losing one electron, form 1+ ions.
• group 2=form ions by losing two electrons, form 2+ ions
• group 6=form ions by gaining two electrons, form 2- ions.
• group 7=form ions by gaining one electron, form 1- ions.

example:

• sodium atom in group 1 loses 1 electron to form sodium ion (Na+).
• oxygen atom in group 6 gains 2 electrons to form an oxide ion (O2-).

Question 4

what is an ion?

Answer 4

a charged particle.

Question 5

what are three types of bonding?

Answer 5

• ionic.
• covalent.
• metallic.

Question 6

what happens when metals and non-metals react together?

Answer 6

the metal atom loses electrons to form positively charged ions. the non-metals gain these electrons to form negatively charged ions. the oppositely charged ions are strongly attached to one another by electrostatic forces. this is called an ionic bond. it holds the ions together to make an ionic compound.

Question 7

what does the dot and cross diagrams show?

Answer 7

how electrons are arranged in an atom or ion, each electron is represented by a dot or a cross.

Question 8

what are the dot and cross diagrams useful for?

Answer 8

for showing how ionic compounds are formed. but they don’t shows the structure of the compound, the size of the ions or how they are arranged. also makes it look different between the crosses and dots but they are all the same.

Question 9

what is the pattern of ions in an ionic compound called?

Answer 9

giant ionic lattice- these are strong electrostatic forces of attraction between oppositely charged ions, these forces are called ionic bonds and act all in different directions.

Question 10

what similar properties does an ionic compound have?

Answer 10

• high melting points.

- high boiling points.

Question 11

why do ionic compounds have high melting points and boiling points?

Answer 11

• lots of energy is needed t break all the strong ionic bonds.
• when they are solid the ions are held in place- solid compounds can’t conduct electricity.
• when they melt the ions are free to move and they can conduct electricity.
• some dissolve in water. the ions move in solution so they can conduct electricity.

Question 12

how to work out empirical formula?

Answer 12

• work out the ions in the compound.
• work out the charges the ions will form.
• balance the charges so the overall charge of the empirical formula will be 0.

Question 13

how do atoms make covalent bonds?

Answer 13

when non-metal atoms bond together, they share pairs of electrons. they only share in their outer shells. the atoms get one extra shared electron for every single covalent bond. each atom usually makes enough covalent bonds to fill up its outer shell makes them very stable.

Question 14

what force is covalent bond?

Answer 14

it is electrostatic bond and very strong.

Question 15

what are the three ways of drawing covalent bonds?

Answer 15

• dot and cross diagrams.
• displayed formulas.
• 3D models.

Question 16

what does the dot and cross diagram show?

Answer 16

• shoes which atoms the electrons in a covalent bond come from.
• electrons in the overlap between two atoms are shared electrons.
• but they don’t show how the atoms are arranged or how big the atoms are compared to each other.

Question 17

what does displayed formulas show?

Answer 17

• shows the covalent bond are single lines between atoms.
• if it’s a single covalent bond = one line
• if it’s double covalent bond = two lines.
• good for showing how atoms are connected in large molecules.
• but they don’t show the 3D structure of the molecule, and which atoms the electrons in the covalent bond have come from.

Question 18

what are 3D models show?

Answer 18

• it shows the atoms, the covalent bonds and how they are arranged.
• but 3D models can be confusing for large molecules and where the electrons in the bonds have come from.

Question 19

what are simple molecules made up of?

Answer 19

they are made up of molecules that contain a few atoms joined together by covalent bonds.

Question 20

what do substances with covalent bonds normally have?

Answer 20

they have a simple molecular structures- where the atoms within the molecules are held together by a very strong covalent bonds.

Question 21

but… what are the forces of attraction?

Answer 21

they are very weak between the molecules.

Question 22

what needs to happen to melt or boil a simple molecular compound?

Answer 22

only needs to break the weak intermolecular forces and not the covalent bonds. melting and boiling points are very low which means it is easy to break the intermolecular forces.

Question 23

what are most molecular substances when they are at room temperature?

Answer 23

they are gases or liquids.

Question 24

what happens when molecules get bigger?

Answer 24

the intermolecular forces get stronger which means more energy is needed to break the forces so the melting and boiling points will increase.

Question 25

what do molecular compounds don’t conduct?

Answer 25

it doesn’t conduct electricity- as they aren’t charged.

Question 26

what is in a polymer?

Answer 26

there are lots of small units which are joined together to form a long molecule. all the atoms are joined together by strong covalent bonds.

Question 27

the small part of a polymer to draw is called what?

Answer 27

the repeating unit. polymer is made up of this unit repeated over and over again.

Question 28

what are the intermolecular forces between polymer molecules like?

Answer 28

they are larger than between simple covalent bonds. this means more energy is needed to break them-so most polymers are solid at room temperature.