Chemical bonding

Question 1

what are the 3 types of chemical bonding

Answer 1

ionic, covalent, metallic

Question 2

what is ionic bonding

Answer 2

the attraction between oppositely charged ions or metals and non- metals

Question 3

what is covalent bonding

Answer 3

covalent bonding involves 2 non-metal atoms sharing one or more pairs of electrons
- positively charged nuclei are attracted to the shared pair of electrons by electrostatic forces, making these bonds very strong

Question 4

what is metallic bonding

Answer 4

the attraction between positively charged ions aand negatively charged delocalized electrons

Question 5

where does metallic bonding take place

Answer 5

in mixtures of metals and alloys

Question 6

Describe cations

Answer 6

-cations are positive ions
-these are created when an atom loses electrons
-the metals in group 1 and 2 can easily lose electrons to be cations

Question 7

describe anions

Answer 7

-anions are negatively charged ions
-created when an atom gains electrons
-The non-metals in Group 7 are most likely to gain electrons to fill up their electron shell and become negatively charged.

Question 8

what are ionic lattices

Answer 8

giant structures that are held together by strong electrostatic forces between the positive and negative ions

Question 9

what are ions

Answer 9

charged particles

Question 10

why do atoms want to gain a full outer shell

Answer 10

so that they become stable

Question 11

advantages and disadvantages of dot cross diagram

Answer 11

advantages
- useful in showing how ionic compounds are formed, how the electrons move

disadvantages
- they don’t show the size of the ions, the structure of the compound or the way the ions are arranged
- doesnt show the forces between the ions

Question 12

properties of ionic compounds

Answer 12

• very high melting points because of the strong electrostatic forces in between the ions, a lot of thermal energy required to break
• when they’re solid, cannot conduct electricity, can only conduct electricity in molten form or dissolved in water, when they are in these forms, the ions are free to move and carry charge

Question 13

advantages and disadvantages of ball stick diagrams

Answer 13

advantages
- shows the regular pattern of an ionic crystal
- shows how all the ions are arranged
- suggests that the crystal extends beyond whats shown in the diagram

disadvantages
- we can’t see the forces in between the ions
- not to scale

Question 14

when does covalent bonding happen

Answer 14

between two non metals e.g H2O or between non-metal elements like Mg2

Question 15

what are simple molecular substances

Answer 15

substances made up of molecules containing a few atoms joined together by covalent bonds

Question 16

common simple molecular substances that I need to know

Answer 16

H2
CL2
O2
N2
H2O
CH4

Question 17

properties of simple molecular substances

Answer 17

• atoms within the molecules held together by very strong covalent bonds
• the forces of attraction between the molecules are very weak
• to melt a simple molecular substance, only need to break weak intermolecular bonds, melting and boiling points very low as the molecules are easily parted
• as molecules get bigger, strength of intermolecular
  increases, therefore melting and boiling points increase
• they don’t conduct electricity as they aren’t charged, so there are no free electrons or ions

Question 18

how does metallic bonding work

Answer 18

• involves delocalized electrons
• the electrons in the outer shells of metal atoms are delocalized ( free to move around ) , there are strong electrostatic forces between the positive ion and shared electrons.
• these forces of attraction hold the atoms together in a regular structure

Question 19

examples of metallic bonding uses

Answer 19

• in metallic elements
• in metal alloys

Question 20

properties of metals

Answer 20

• strong
• high melting and boiling points
• most are malleable
• most are solid at room temp

Question 21

why do we use alloys rather than pure metals

Answer 21

• pure metals are often too soft, mixed with other metals to give them different properties like hardness
• mixing elements with pure metals will distort the layers of the metal atoms, making it harder for the metal atoms to slide over each other, increasing hardness again

Question 22

what are ionic compounds

Answer 22

a giant structure of ions

Question 23

Why are metals good conductors

Answer 23

because the delocalized electron in the metal carry electrical charge through the metal, energy in transferred by the delocalized electrons

Question 24

why are metals solid at room temp

Answer 24

because the electrostatic forces between the metal atoms and delocalized electron are very strong, needs a lot of energy to break

Question 25

why are metals malleable ( able to be bent into other shapes etc)

Answer 25

because the layers of atoms in a metal can slide over each other

Question 26

what does the energy needed to change state depends on

Answer 26

the strength of the forces between the particles of the substance.

Question 27

what are some limitations of particle theory diagrams

Answer 27

• particles are not spheres,
• particles are not solid or inelastic
• the model doesnt show the forces between the particles, so theres no way of knowing how strong they are

Question 28

why do elements react

Answer 28

• to achieve a full outer shell
• to achieve the electronic structure of a noble gas