structure and bonding chemistry

Describe properties of solids

Fixed shape and volume

Cannot be compressed

Particles in solids are very close together

Fixed arrangement

Cannot move around but vibrate constantly

Describe liquids

Fixed volume

Can flow and change shape

Particles close together but can move past each other other → constantly changing and random particle arrangement

Describe gases

No fixed shape or volume

Cannot be compressed easily

Particles Move around at high speeds and in random directions → random arrangement

How do substances change state?

The substance gets hotter and particles vibrate more

Eventually vibrations become strong enough to break the bonds holding particles together

Are changes of state physical or chemical changes and why?

Physical → reversible

Substances with higher melting and boiling points have _______ forces operating between them.

Stronger

Why does the temperature of a substance remain constant for a short while at the melting and boiling points?

Enough energy transferred from surroundings for forces holding particles together to break the bonds.

How does cooling substances change their state?

Energy transferred to surroundings as stronger forces form between particles.

What are the limitations of the particle model?

Assumes that particles are solid spheres with no forces between them → useful when comparing properties but particles that make up substances vary in size and type (ions, molecules etc), also atoms mostly are empty space and not solid at all

Ionic bonding occurs between…

Metals and non-metals

What holds together atoms in ionic bonding?

Strong forces of electrostatic attraction that acts in all directions

Ionic bonds result in the arrangement of ions called a….

Giant structure/ lattice

What charge ions do groups 1,2,3,5,6 and 7 form?

1+, 2+, 3+, 3-, 2-, 1-

Why do ionic compounds have higher melting and melting and boiling points?

There are lots of strong ionic bonds to break and you must overcome a the electrostatic forces of attraction acting in all directions so lots of energy is required to break the bonds.

How can melted ions carry their electrical charge?

Ions move freely in the liquid and are attracted to the oppositely charged electrodes in the liquid

Why can’t solid ionic compounds conduct electricity?

The ions are held in fixed positions and cannot move around but only can vibrate on the spot