Term 2 Test (Chemistry) Flashcards
What is the difference between elements and compounds?
Elements are pure substances made up of only one type of atom, whereas compounds are made up of multiple chemicals that are chemically combined in fixed proportions.
Where are metallic elements found on the Periodic Table and what properties do they compare with non-metallic elements?
Metallic elements are mostly found on the left and centre of the Periodic Table. Metallic elements have a shiny lustre, and conduct heat and electricity. They can be bent and stretched, being flexible, whereas non-metallic elements are the opposite.
How do you represent a chemical formula by using symbols for elements?
Each new capitol letter represents a new element, and the sub-number tells how many atoms of that element are in the compound. Example: H2O = 2 Hydrogen + 1 Oxygen
How do you represent a mixture by a percentage?
Amount of element being measured divided by total weight of mixture, then multiplied by 100 = %
e.g. a mixture of 250g of salt, sand, and iron filings has 50g of salt, 175g of sand, and 25g of iron filings. The percentage composition of sand in the mixture will be the mass of sand (175g) over the total mass (250g) = ((175g/250g)*100)% = 70% So the mixture is made up of 70% sand).
What is the difference between atoms, compounds, molecules and mixtures?
Atoms are the smallest particle to exist that makes up everything. A compound is made up of 2 or more different chemical elements combined in a fixed ratio. A molecule is a group of 2 or more atoms combined by a chemical bond. A mixture is made up of multiple substances that are not chemically bonded.
What is the atomic number?
The number shown at the top corner of each element on the periodic table, to symbolise how many protons in the nucleus of the atom.
What factors indicate a chemical change?
Factors that indicate a chemical change include colour change, temperature change, aroma change, production of gas and a solid known as a precipitate appearing.
Is changing state considered a chemical change or a physical change?
It is considered a physical change, because between freezing water to a solid, melting it to a liquid and evaporating it to a gas, it’s chemical make-up does not change.
What is an element?
A pure substance with only one type of atom.
How can indicators of chemical change assist with pool water testing?
Using a chemical formula that reacts to pH in the pool water can display a visible change that defines the amount of pH in the water.
Define combustion and corrosion.
Combustion is a chemical reaction resulting in the release of energy, light or heat, like a sparkler.
Corrosion is the combnination of oxygen and a metal to create a metal compound such as rust.
How to calculate density?
Density = Mass divided by Volume.
d = m/v
