Part 1 - The Importance Of Metals Flashcards
(32 cards)
What are the main characteristics of metals?
Dense Lustrous (shiny) Good conductors of heat Good conductors of electricity Can be shaped by physical forces
What are the 2 main ways metals can be shaped by physical forces?
Can be deformed under tensile stress e.g. By stretching - a property known as ductility
Deformed under compressive stress, e.g. By hammering into thin sheets - a property known as malleability
What is the definition of malleability?
The property of something that can be worked or shaped or hammered under pressure without breaking
What is the definition of ductility?
The ability of a material to deform plastically without fracturing. Measured by elongation or reduction of an area in a tensile test, by height of cupping in an erichsen test, or by other means.
What is ppm?
Parts per million
How do you calculate parts per million from a percentage?
If you have the percentage then you have it as a fraction.
E.g. 0.012/100
You can therefore work this out in how many parts per million by multiplying by 10
120/100000
How is a billion expressed in scientific notation?
10^9
What is ppb?
Parts per billion
What are alloys?
Alloys are blends of one metallic element with one or more others
E.g. Alloy of copper and tin
What are brass, steep and stainless steel made of?
These are all alloys
Brass - copper and zinc
Steel- manly iron and also contains carbon and other smaller amounts of other elements
Stainless steel- steel with a sizeable portion of nickel and chromium
What is the unity of purity for gold?
Karat
How many karats make up a while in terms of units for gold?
24
1/24 is one unit of gold
What is a lattice structure?
It is an ongoing arrangement of metal atoms in a three-dimensional regular ordered pattern
How are nuclei and electrons arranged in metals compared to other materials?
The electrons in the outer shells do not remain in proximity of a specific nucleus.
In bulk metals, these electrons, rather than being associated with any particular metal atom, can be thought to be part of a shared sea of electrons that move freely.
What are delocalised electrons?
They are electrons that move freely across atoms.
They do not stay in proximity to a specific nucleus
What is metallic bonding?
It is the attraction between delocalised electrons and the positively charged nuclei.
Why do metals have high melting temperatures?
The metallic bonding is strong and occurs in all directions. Breaking this attraction is difficult, and this is the reason that metals have high melting temperatures.
Why are metals good conductors of heat and electricity?
Because of the freely moving electrons, they facilitate the transfer of charge or heat through the material
What is an electric current?
It is the flow of negatively charged electrons through a conductor.
What is voltage?
In a battery it is considered as the ‘push’ exerted on electrons moving around the circuit.
How do delocalised electrons help a metal with its malleability?
The bonding occurs in every direction throughout the metal enabling atoms to roll easily over each other without breaking any bonds when stress is applied.
What is the number of a shell containing electrons also known as?
Principal quantum number
n
How can you identify a metal when it is impart to a flame?
By the colour change
As an electron moves outwards from the nucleus (so as the principal quantum number increases) what happens to the energy of the electron?
It also increases
