properties of matter

Question 1

atom

Answer 1

elements are made of tiny particles called atoms

Question 2

molecule

Answer 2

two or more atoms

Question 3

kinetic energy

Answer 3

energy possessed by a body solely in account of its motion

Question 4

potential energy

Answer 4

energy possessed by a system of bodies based on their positions and force fields between them

Question 5

kinetic energy symbol and units

Answer 5

EK
JOULES

Question 6

atomic structure

Answer 6

• protons amd neutrons in nucleus
• electrons in shells

Question 7

moles

Answer 7

number of molecules in a molecular mass in grams of a substance

Question 8

avogadros constant

Answer 8

6.02 x 10^23

Question 9

ionic bonds

Answer 9

• loosely held outer electrons that are transferred between atoms forming oppositely charged ions
• electrostatic attraction
• strong and high melting points

Question 10

covalent bonds

Answer 10

• outer electron sharing between two or more atoms
• strong

Question 11

metallic bonds

Answer 11

• sea of delocalised electrons
• strong electrostatic attraction
• electrical conductivity

Question 12

van der waals

Answer 12

• asymmetry in electron clouds around atoms leads to charge dipoles
• opposite ends of dipoles form weak attractive forced between neighbouring molecules
• in liquid surface tension

Question 13

density of element depends on

Answer 13

mass of each of its atoms
the way the atoms are packed

Question 14

solids

Answer 14

atoms in close proximity
atoms vibrate about fixed positions
defined shape

Question 15

crystalline solids

Answer 15

all metals and most minerals
arranged in regular relating pattern
face centered cubic- copper
body centered cubic - sodium
hexagonal close-packed - zinc
defined melting point - at one exact temp

Question 16

amorphous solids

Answer 16

• without shape or form
• no long range order in particle arrangement
• no defined melting point- at a range of temperatures
  eg glass and plastic

Question 17

polymeric solids

Answer 17

• long chains of carbon atoms bonded to hydrogen and other atoms
• repeating monomers
• can be natural eg dna or synthetic such as nylon

Question 18

polymers

Answer 18

• branching and cross linking effects physical properties such as melting point
• can be crystalline, amorphous or both and determine mechanical properties

Question 19

mechanical properties of polymers

Answer 19

strength- maximum force a metrical can withstand without breaking
stiffness- resistance to deformation under applied forces
brittleness- tendency to crack under applied forces
ductility- ability to undergo permanent deformation without fracture - be drawn inti a wire without breaking

Question 20

stress

Answer 20

force acting per unit cross-sectional area of material

Question 21

strain

Answer 21

extension produced per unit length

Question 22

hookes law

Answer 22

force needed to extend a spring by a certain distance is proportional to that distance

Question 23

potential energy 4 types

Answer 23

elastic
gravitation
chemical
electrical

Question 24

atomic explanation of plastic deformation

Answer 24

• plastic strain and ductility is property of crystalline materials
• permanent plastic deformation could be explained in terms of slippage of ion layers and breaking of atomic bonds

Question 25

atomic explanation of plastic deformation dislocation theory

Answer 25

plastic strain of ductile materials can be explained by propagation of crystal dislocations

Question 26

strengthening of metals

Answer 26

alloying grain boundary strengthening

Question 27

composite materials

Answer 27

combining materials to enhance mechanical properties

Question 28

fiber reinforced composites

Answer 28

nature such as wood connective tissue cornea

Question 29

heat

Answer 29

- energy transferred from a body at higher temperature to one at a lower temp by conduction, convection or radiation - heating solids causes increased in KE - if sufficient heat is transferred to overcome bonding energy, melting occurs

Question 30

ideal gas

Answer 30

theoretical has composed of a set of randomly moving non interacting point particles can be described by pressure volume and temperature

Question 31

charles law

Answer 31

the volume of a fixed mass of gas at constant temperature is directly proportional to its absolute temperature

Question 32

boyles law

Answer 32

the pressure of a fixed mass of gas at constant temperature is inversely proportional to its volume

Question 33

gay-lussacs law

Answer 33

pressure of a fixed mass of gas at constant volume is directly proportional to its absolute temperature

Question 34

liquids

Answer 34

- atoms in close proximity but can move freely and randomly

Question 35

pressure

Answer 35

force per unit area acting at right angles to a surface

Question 36

surface tension

Answer 36

amount of force acting along a line on the surface of a liquid, pulling it tight, molecules pulled inwards, measured per unit length