Materials

Question 1

Define mass number and atomic number and calculate the number of protons/neutrons/electrons when given atomic number

Answer 1

Atomic number= number of protons in an atom

Mass number= number of protons + neutrons in an atom

Question 2

Describe the structure of molecules in crystal lattices for elements

Answer 2

Two categories within elements and compounds these are molecular or crystal lattices.
Molecular elements;
Molecular elements are made of molecules
Only one type of atom
Crystal lattice elements;
Carbon is the only non metal that can be a crystal lattice element
Many atoms in well organised structure of the same type are formed

Question 3

Classify compounds into groups based on common names and chemical characteristics; ionic, molecular (covalent), acids and bases.

Answer 3

Ions= lose or gain electrons to become electrically charged
Ionic = metal + non metal / take electrons
-positively charged ions are called cations
-negatively charged ions are called anion
Molecular or covalent = sharing of electron pairs in an atom
-made up of two or more atoms chemically joined together.
Acid= substance that releases hydrogens ions (H+) into an aqueous solution
Base= substance that releases hydroxide ions (OH-)

Question 4

Describe properties and give examples of metals, non-metals and metalloids

Answer 4

Metals= soft, lustrous, malleable, ductile, good conductors of heat, solid at room temperature, dense
Non-metals= found naturally as gases, poor conductors of heat, brittle, dull, low boiling, melting points
Metalloids= act like non-metals, semi conductors of heat, can occasionally conduct electricity

Question 5

Describe the pH scale no it’s use and the effect of acids and bases on indicators

Answer 5

Water is neutral (pH of 7)
Acids have a pH or less than 7
Bases/alkaline solution have 7+ pH level
Indicators= chemicals that change colours to show whether a substance is acidic, neutral or basic.

Question 6

Describe the structure of molecules in crystal lattices for compounds

Answer 6

Molecular compounds
Molecules can either be small or very large
Made of more than one type of atom

Crystal lattice compounds
Many compounds are crystal lattices
Made of many atoms of more than one type of atoms