Design materials and chemical equations Flashcards
Design materials
design materials are materials created by humans to have certain properties in order to perform a function.
The properties of a substance are determined by ____
its molecular structure
Examples of certain properties
- Strength
- Flexibility
- Hardness
- Transparency
Aspects of molecular structure
- Composition
- Bonding
- Crystal structure
Composition
The composition of a substance is the particular types of atoms and molecules in a substance.
Bonding
The bonding in a substance is the type and strength of intramolecular and intermolecular forces between the particles.
Crystal structure
The crystal structure is the arrangement or order of the atoms and molecules in the substance.
Crystalline structure
well ordered with repeating symmetrical patterns. Substances with a crystalline structure are stronger and stiffer.
Non-crystalline structure (amorphous)
when atoms and molecules are randomly arranged. Amorphous structures are weaker but more flexible.
Metal bonding type(s)
Metallic
Ceramic bonding type(s)
Ionic and covalent
Polymer bonding type(s)
Covalent and intermolecular
Metals are strong ____
because the negative “electron sea” completely surrounds the positive ions.
Metals are conductive_____
because the “electron sea” can flow from atom to atom.
Metals are not transparent____
because metals hold onto their electrons loosely and the loose electrons can vibrate at many frequencies so metals have more available energy states and can absorb more EM radiation.
Metals are reshapeable______
because the metal ions can move around in the “electron sea” without breaking bonds
Metals tend to_____
bend instead of crack/shatter
Metal crystals and alloys (2)
- Metals that have a crystal structure are stronger, but less able to flex
- Borders between metal crystals are called grains, which are weak spots and can be strengthed by adding an atom of a different metal. This type of metal is called an alloy
Ceramics (2)
- Ceramics are made of both metal and non-metal atoms, bonded by ionic and covalent bonds.
- Ceramics and glasses have the similar composition, but ceramics have a crystalline structure while glass has an amorphous structure.
Ceramics are hard___
because the positive and negative ions alternate with very strong forces meaning they are where they want to be so they don’t want to move.
Ceramics are not reshapable_____
because atoms cannot move without breaking bonds so ceramics tend to crack instead of bending/deforming.
Ceramics are transparent ____
because the electrons in ceramics and glasses are held tightly so they absorb few frequencies of EM radiation.
Ceramics are not conductive___
because they hold onto electrons tightly, not allowing electricity/heat to flow through.
Polymers (4)
- Polymers are long chains of atoms that are covalently bonded together.
- Polymers typically have a “backbone” made from carbon
- Polymers connect to each other by intermolecular forces
- Cross-linking makes the substance stiffer and stronger but less flexible
Polymers are strong to tension forces____
because of the long chain molecules but are weak to other forces, unless cross-linked.
Polymers are not conductive _____
because the electrons are not free to move.
Polymers are transparent____
because the electrons in polymers are held more tightly, so they absorb few frequencies of EM radiation
Polymers are flexible____
because the polymer molecules are long and thin, so they can be easily bent unless cross-linked.
Law of conservation of mass
Mass cannot be created or destroyed but it can change forms.
Chemical reactions
In a chemical reaction new substances are created by breaking old chemical bonds and making new chemical bonds.
Reactants
Substances that exist before the reaction.
Products
Substances that exist after the reaction.
