Science Substances Sem 2 Flashcards
Atoms
- Splitting Atoms creates nuclear power and atomic bombs.
- Smashing atoms together is where the sun gets energy from
- Made up of protons, neutrons and electrons
Protons and neutrons form the nucleus together
Metallic Metals
Elements that are metal. They have the following properties:
- Solids at room temperature (Except for
Hg)
- Can be made shiny or lustrous
- Conduct heat and electricity
- Can be beaten into shape or stretched into wire
Melts at very high temperatures (except for Hg)
Non metallic Elements
19 non-metals. These have the folliwing properties:
- Dull, not shiny
- Breaks or crumbles when bent
- Melts at low temperature
Do not conduct heat or electricity
Metalloids
A metalloid is a type of chemical element which has a preponderance of properties in between, or that are a mixture of, those of metals and nonmetals.
Alkali Metals
Group 1. Very reactive in water
Alkaline earth Metals
Group 2. Less reactive than alkali metals but still have all the metal properties
Transition Metals
In the block between group 2 and 13. They have metallic properties. Have many interesting properties and many form colorful compounds
Halogens
Group 17. They are very reactive. From left to right: Chlorine (gas), Bromine (liquid) and Lodine (solid)
Noble Gases
Group 18. All very unreactive but glow when exposed to electricity under special conditions
Monatomic Elements
An element that is made up of many individual atoms. Only 6 of these. Includes:
- Helium
- Neon
- Argon
- Krypton
- Xenon
- Radon
Molecular Elements
Most non-metallic elements are made up of molecules. Molecules are clusters of 2 or more atoms bonded together. In these elements, all molecules are identical.
Crystal Lattices
Are grid like structures
Molecular Formula
Molecular formulas are formulas for substances that are molecules. Other compounds that aren’t formulas for substances that are not molecules can also have formulas that represent the atoms in the compound
Mixtures
When two or more substances mix but do not form chemical bonds, it form a mixture. Air is a mixture of nitrogen, oxygen and carbon dioxide (a compound). Properties of a mixture is the same as the properties of its parts.
Separating compounds
Breaking chemical bonds. Energy needed: Electricity, extreme heat, other chemicals
Physical Change
Explains changes of state by looking at the relationship between how the particles move and attraction between the particles. Change between solids liquid and gases.
Chemical Change
The key difference between a physical and chemical change is that new substances are produced during a chemical change.
Evidence:
- Solid precipitate out of solution
- An odour or bubbles or gases being released
- Light or heat being released
- A permanent change of colour
Electricity used or produced
Colour Changes
This happens because the new substance produced by the chemical change is a different colour to what you started.
Gas Produced
Produced during a chemical change may be observed as bubbles, a new smell or perhaps smoke
Precipitate Forms
Any new solid is produced when two solutions are mixed.
What energy is released
Energy plays an important role in chemical changes. Some release heat, light or both
Energy is absorbed
Some chemical changes absorb heat, causing their surroundings to cool.
Chemical Reactions
During chemical change, old substances disappear and new substances form. The only way this can occur is if the atoms in the old substances rearrange to form the new substances.
Reactants
Old substances
Products
New substances
4 types of chemical reactions
Combustion, Photosynthesis, , Respiration, Corrosion
Combustion
Is the term given to any chemical reaction that involves burning O2.
Photosynthesis
Most biological chemical reaction. A series of chemical reactions that uses sunlight energy to convert H2O and CO2 into O2 and energy.
Carbon dioxide + Water ———– Oxygen + glucose
Respiration
The process of obtaining energy from food.
Corrosion
Type of reaction that can cause damage to metals.
Flammability
Describes how easily a substance undergoes combustion.
