Important Materials Flashcards
Define a metal
A metal is a substance that is typically solid (except for mercury), shiny, and a good conductor of electricity and heat. Metals are malleable, ductile, and have a high melting point. They tend to lose electrons in chemical reactions, forming positive ions (cations).
Define a non-metal
Non-metals are elements that lack the characteristics of metals. They are typically poor conductors of heat and electricity, are not lustrous, and are often brittle when solid. Non-metals tend to gain electrons in chemical reactions, forming negative ions (anions).
Define a metalloid
Metalloids are elements that have properties intermediate between metals and non-metals. They can exhibit characteristics of both categories, depending on the conditions. For example, silicon is a metalloid that is shiny like a metal but brittle like a non-metal and a semiconductor of electricity.
Properties of a Metal
Good electrical and thermal conductivity
High melting and boiling points
Malleable and ductile
Lustrous (shiny)
Tend to lose electrons and form positive ions
Properties of a Non-metal
Poor electrical and thermal conductivity
Low melting and boiling points
Brittle in solid form
Dull appearance
Tend to gain electrons and form negative ions
Define an alloy
An alloy is a mixture of two or more elements, where at least one element is a metal. Alloys are designed to have enhanced properties compared to the pure metals they contain.
Examples of alloys and their uses
Steel (Iron + Carbon): Used in construction, tools, and automotive industries.
Brass (Copper + Zinc): Used in musical instruments, decorative items, and plumbing fixtures.
Bronze (Copper + Tin): Used in coins, sculptures, and bearings.
What are the different types of steel (composition, differences, uses)
Carbon Steel: Composed primarily of iron and carbon. It’s classified into low, medium, and high carbon steels. Used in construction, pipelines, and machinery.
Stainless Steel: Contains iron, carbon, and chromium (and sometimes nickel). Known for its corrosion resistance, used in kitchen appliances, medical instruments, and cutlery.
Alloy Steel: Includes additional alloying elements like manganese, silicon, and vanadium. Used in automotive parts, power generators, and pipelines.
What is nanotechnology?
Nanotechnology is the manipulation of matter on an atomic, molecular, and supramolecular scale, typically below 100 nanometers. It involves creating and using materials, devices, and systems with novel properties and functions due to their small size.
How small is a nanometre?
A nanometer (nm) is one-billionth of a meter (0.000000001 m). It’s the scale at which atoms and molecules operate.
Hydrophilic vs Hydrophobic
Hydrophilic:
Substances that are attracted to water and can dissolve or absorb water easily.
Hydrophobic:
Substances that repel water and do not dissolve or mix well with water.
What is the pH scale?
The pH scale measures the acidity or basicity of a solution. It ranges from 0 to 14, with 7 being neutral. Values below 7 indicate acidity, and values above 7 indicate basicity (alkalinity).
What is a base?
A base is a substance that releases hydroxide ions (OH-). A base that can dissolve in water is also referred to as alkali. If an alkali is dissolved in water, the solution can be called an alkaline solution.
What is an acid?
An acid is a substance that releases hydrogen ions (H+) into an aqueous solution.
What ways can pH be measured?
Litmus paper: Changes color in acidic or basic solutions.
pH meter: Provides a precise digital measurement.
Universal indicator: Changes color according to the pH level.
Define lusterous
Having a shiny surface that reflects light.
Define malleable
Capable of being hammered or pressed into shape without breaking.
Define ductile
Able to be drawn into thin wires.
Define quenching
Rapid cooling of a hot metal to set its structure.
Define annealing
Heating and then slowly cooling a metal to make it more workable.
Define tempering
Heating and then slowly cooling a metal to reduce brittleness.
List 2 pure metals, their element symbol and their use
Gold (Au): Used in jewelry and electronics.
Silver (Ag): Used in jewelry, electronics, and photography.
What is the only metal that is a liquid at normal room temperature?
Mercury
What scale is used to show the purity of gold? Explain it
The purity of gold is measured in karats. Pure gold is 24 karats. The scale measures the proportion of gold in an alloy out of 24 parts. For example, 18-karat gold is 18 parts gold and 6 parts other metals.
Why is gold rarely used in its natural form?
Gold is rarely used in its natural form (24 karats) because it is too soft. It is often alloyed with other metals to increase its hardness for practical uses.
List 3 properties of acids
Corrosive
Sour
Conduct Electricity
List 3 properties of bases
Bitter taste
Slippery feel
Can conduct electricity
List 1 strong acid and 1 weak acid and state what they are used for
Strong Acid: Hydrochloric acid (HCl) - Used in cleaning and refining metal.
Weak Acid: Acetic acid (CH₃COOH) - Used in vinegar for cooking.
List 1 strong base and 1 weak base and state what they are used for
Strong Base: Sodium hydroxide (NaOH) - Used in soap making.
Weak Base: Ammonia (NH₃) - Used in household cleaners.
List 2 foods that are acidic
Lemons and oranges
List 2 foods that are alkaline
Spinach and cucumbers
What is the cause of heartburn, and how can you fix this issue? (explain the science behind this)
Heartburn is caused by stomach acid (hydrochloric acid) refluxing into the esophagus. Antacids (which are basic) can neutralize this acid, relieving the discomfort.
Define endothermic and exothermic reactions
Endothermic: A reaction that absorbs energy (heat) from the surroundings.
Exothermic: A reaction that releases energy (heat) into the surroundings.
Define combustion
A chemical reaction that occurs when a substance reacts with oxygen, releasing energy as heat and light.
Define reactants and products.
Reactants: The starting substances in a chemical reaction.
Products: The substances formed as a result of a chemical reaction.
What is photosynthesis?
A process in plants that converts carbon dioxide and water into glucose and oxygen using sunlight.
What is respiration?
A process in living organisms that converts glucose and oxygen into energy, carbon dioxide, and water.
Define corrosion
The gradual destruction of materials, usually metals, by chemical reactions with the environment.
Define anodizing
A process that increases the thickness of the natural oxide layer on the surface of metal parts, often used to prevent corrosion.
What is incomplete combustion?
A combustion reaction where there is not enough oxygen, resulting in the production of carbon monoxide, water, and sometimes soot.
What is neutralisation
A chemical reaction between an acid and a base that produces water and a salt.
What substance is always required for combustion to occur?
Oxygen
What occurs if there is not enough of oxygen?
Incomplete combustion occurs, which can produce carbon monoxide and soot, making the reaction less efficient and potentially dangerous.
What is the word equation and chemical equation for photosynthesis?
Word Equation: Carbon dioxide + Water → Glucose + Oxygen
Chemical Equation:
6CO2 + 6H2O → C6H12O6 + 6O2
What is the word equation and chemical equation for respiration?
Word Equation: Glucose + Oxygen → Carbon dioxide + Water + Energy
Chemical Equation: C6H12O6 + 6O2 → 6CO2 + 6H2O
