Structure and bonding

Question 1

what takes place at the melting point of a solid

Answer 1

-freezing and melting

Question 2

what takes place between a lquid and a gas at the boiling point

Answer 2

condensing and boiling

Question 3

what does the amount of energy needed to change state depend on

Answer 3

strength of forces between the particles of the substance

Question 4

the stronger the forces between the particles…..

Answer 4

the higher the melting point and boiling point

Question 5

gas particles

Answer 5

• widely spaced
• constant quick motion
• collisions are frequent and elastic
• weak forces between the particles

Question 6

liquid particles

Answer 6

closely spaced
still in constant motion
constantly colliding
forces between particles less stronger than in solids

Question 7

solid particles

Answer 7

do not move around freely

vibrate in a fixed position only

Question 8

the simple model

Answer 8

small solid spheres
limitations of this model are that there are no forces between the particles shown
atoms molecules and ions are not solid spheres

Question 9

what do pure elements and compounds boil at

Answer 9

specific temperatures

Question 10

a pure substance will:

Answer 10

melt or boil at a specific temperature

whereas a mixture melts or boils over a range of temperatures it does not have a sharp melting point.

Question 11

solid melting curve

Answer 11

-temperature rises when solid starts to melt
a pure solid will melt at a fixed temperature and the line will stay horizontal when its melting
the temperature does not rise when the solid is melting because heat absorbed to break the bonds between solid particles

Question 12

ionic bonding between a non metal and a metal

Answer 12

when a metal atom reacts with a non metal atom, electrons in the outer energy level are transferred

Question 13

metal atoms

Answer 13

metal atoms lose electrons to form positive ions

and non metal atoms gain electrons to form negatively charged ions

Question 14

ions produced by metals in group 1 2 and non metals in 6 and 7

Answer 14

have the electronic structure of a noble gas

Question 15

sodium chloride example

Answer 15

in sodium chloride sodium atom loses one electron away forming a 1+ ion the chlorine atom gains one electron to form a 1- ion
the ionic bond is the force of attraction between the oppositely charged ions.

Question 16

ionic compound

Answer 16

total positive charge should be the same as the total negatuve charge

Question 17

compound ions

Answer 17

some groups of elements have a charge- these are called compound ions
carbonates- co3 2- , sulfates so4 2- mitrates no3 -
ammonium nh4+

Question 18

when to use brackets

Answer 18

when more than one compound ion is used in a formula we put the ion inside in brackets and put the number outside brackets.

Question 19

giant ionic structure

Answer 19

an ionic compound is a giant structure of ions
ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions. these forces act in all directions in the lattice this is called ionic bonding

Question 20

there are two models to present ionic bonding

Answer 20

space filling

ball and stick model

Question 21

advantages and disadvantages of ball and stick

Answer 21

advanatages- shows electrostatic forces of attraction
allows to clearly see ions in 3 dimensions
disadvantage- does not show sizes of ions correctly ions are shown as spaced when in reality they are much closer together.

Question 22

space flling

advantages and disadvantages

Answer 22

sizes of each ion shown correctly shows how closely packed ions are
disadvantages- electrostatic forces of attraction are not shpwn

Question 23

both only show

Answer 23

both ball and stick and space filling models only show a tiny part of the crystal lattice both give a mistaken impression on sizes of these structures

Question 24

properties of ionic compounds

Answer 24

high melting points
high boiling points
because large amounts of energy required to break the strong electrostatic forces of attraction between the oppositely charged ions

Question 25

when in solid cannot…

Answer 25

when in a solid cannot coduct electricity because ions are fixed in place
when melted or dissolved in water, ionic compounds can conduct electricity because ions are free to move and carry a charge

Question 26

never use

Answer 26

always use the term ions when describing ionic compounds never use terms delocalised electrons, intermolecular forces, or molecules.

Question 27

what is the emperical formula

Answer 27

simplest ratio of ions in a compound