material science mid 1

what are the 5 classifications of materials?

metals, ceramics, polymers, composites and advanced metals

what are the properties of metals?

strong and ductile, good electrical and thermal conductors. they are made up of one or more metallic elements and sometimes contain non metal elements

what are the properties of ceramics?

hard and heat resistant, and brittle. made up of compounds between metals and non metals

what are the properties of polymers?

lightweight and flexible, they have a low melting temperature. made up of organic compounds. are extremely ductile. are unreactive.

what are the properties of composites?

made up of two or more materials, their properties are a combination of the properties of the materials they are made up of.

what are the properties of advanced materials?

materials designed for high-tech applications. made up of all kinds of materials

what are the steps to extracting metal from ores?

mining, crushing and grinding, smelting, refining

what ore is iron found in?

hematite, magnetite

what ore is copper found in?

malachite, chalcopyrite w

what ore is gold found in?

in river sediments

what ore is aluminum found in?

bauxite

what ore is silver found in?

silver ore

What is an ore

a rock that contains metal that can be extracted

Why are most metals not found in pure form in nature?

Because metals react with oxygen and other elements and form compounds

Give one example of a metal and its ore

Copper → found in malachite , Iron → found in hematite

What is the purpose of metal extraction?

To separate pure metal from the ore so we can use it.

What is the difference between mineral and ore?

A mineral is any natural substance in the Earth

An ore is a mineral that contains enough metal to be useful and extracted economically

Why is copper often found as green minerals?

Because copper reacts with oxygen, water, and carbon dioxide and forms green compounds.

Why is gold sometimes found in pure form?

Gold does not react easily with other elements, so it can remain pure.

Why is extracting metal from ore expensive?

Because it needs machines, energy, and high temperature

What happens if impurities are not removed?

The metal becomes weak or not suitable for use.

Which is easier to extract: Iron or Gold? Why?

Gold is easier because it is often found pure.

How does material choice affect energy during extraction?

Some materials need more heat and energy to extract.

what are derived metals?

metals that are made from natural metals by: Mixing metals together, or adding small amounts of other elements

why do we use derived metals instead of pure metals?

Because pure natural metals are often too soft or weak

what are ferrous metals?

metals that have iron as their main constituent

what are non-ferrous metals?

metals that don’t have iron as their main constituent

give examples of ferrous metals

cast iron, steel, alloy steel and wrought iron

what are the four components of material science?

processing, structure, properties and performance

what is the processing component of material science?

it is any action done to a material to change its shape, structure or properties. (heating, cooling, welding or casting)

what is the structures component of material science?

the process of analyzing a materials structure at different scales. (crystal structure, grain size or microstructure)

what is the properties component of material science?

a process of testing a materials response or behavior to extreme stimuli. (strength, hardness, ductility and toughness)

what is the performance component of material science?

the process of testing a materials actual performance under actual service conditions. (buildings, bridges, cars and machines)

what is the difference between atomic structure and interatomic bonding?

atomic structure shows us what is inside ONE atom, while interatomic bonding shows us how atoms connect to each other.

how many grams is one amu

1.66054e-24wh

what is an anion?

a negative ion. (an atom that has gained electrons)

what is a cation?

a positive ion. (an atom that has lost electrons)

what is an isotope?

atoms of the same element that have the same number of protons but a different number of neutrons.

what are bonding forces?

the main forces that hold atoms together. they are made up of either repulsive forces or attractive forces/

when do bonds form?

when repulsive forces = attractive forces

what is bonding energy?

the amount of energy needed to break the bonds between atoms

what does bonding energy tell us?

how strong a bond is and how stable the material is.

what makes the mass number and atomic mass different?

1. the mass defect: the missing mass

2. binding energy: the energy produced from that missing mass to the hold the nucleus

what are the two main trypes of bonding?

priary bonds (strong bonds) and secondary bonds (weak bonds)

how do ionic bonds form?

due to differences in electronegativities one atom losses electrons and the other atom gains those electrons forming an ionic bond

what are coulombic attractive forces?

the attractive forces between + and - ions

how do covalent bonds form?

due to small differences in electronegativity two or more atoms share electrons

what is metallic bonding?

strong electrostatic forces of attraction between positive metal ions and a sea of delocalized electrons

what are van der waals bonds?

occurs when there is a attraction between the - and + sides of two dipoles

what are the factors affecting atomic stability?

1. electronic structure (more stable with a more full outter shell)

2. types of bonds (when bonds for energy is reduced to a lower energy level)

3. atomic size (forces of attraction increase between valence electrons and nucleus in smaller atoms)

4. charge balance (ions attract and reple more than neutral atoms)

what are the key factros affecting atomic bonding?

1. electronegativity differences (determines bond type and different properties)

2. valence electrons (determins bonding tendency

3. atomic size (determins bonding strength)

List the classified structure of materials

Sub atomic

Atomic

Bonding

Crystal

Defects

Micro

Macro

Material components

What is a crystalline arrangement?

Material with long range order of repeated atoms

What is an amorphous arrangement?

Short range order of atoms that are non periodic

What is the unit cell?

The basic building block of the crystal structure

What are the 7 crystal systems?

1. Cubic

2. Hexagonal

3. Tetragonal

4. Original

5. Orthor - hombic

6. Triclinic

7. Monoclinic

What are the parameters of cubic?

a = b = c

Alpha = beta = gamma = 90

What are the parameters of hexagonal close packed structure

a = b = c

Alpha = beta = 90, gamma =120

Why do metallic structures form dense packings?

Metallic bonding is non directional and can slide in layers, usually only one element is present so atomic radii is similar, the electron cloud shields off the nuclei from repulsive forces

What is coordination number?

The number of atoms touching other atoms in different unit cells

Why do atoms minimize empty space?

• fewer gaps lead to more efficient structures

• Atoms arrange themselves where total my is lowest

• A stable distribution is stronger against things like high temp, load and defects

SC

Rare low packing density

Coordination number = 6

Atoms per unit cell = 1

Atomic packing factor (APF)

How much space atoms fill inside the unit cell

What is the stacking pattern of SC

AAAA

BCC

Coordination number = 8

Number of atoms per unit cell = 2

Body diagonal

The line that goes from one corner of the cube to the opposite corner through the center

BCC stacking sequence

ABABA

Close packing planes

Atomic layers where atoms are packed as tightly as possible

Give examples of secondary bonds

Van der waals and hydrogen bonds

Give examples of primary bonds

Ionic, covalent and metallic bonds