C2a Topic 1

Question 1

Structure of atom

Answer 1

- the nucleus
contains protons and nuetrons
overall positive charge 
- electrons
move around the nucleus
negative charge
occupy shells
- no of protons = no of electrons but opposite charge
e.g nitrogen has 7 protons so it has 7 electrons
- proton mass = 1 , charge = +1
- neutron mass = 1 , charge = 0
- electron mass = 1/2000 , charge = -1

Question 2

elements

Answer 2

• atomic number shows how many protons there are, no two elements have the same amount if protons
• atomic no also shows how many electrons are
• mass number is the total no of protons and neutrons. neutrons = mass number - atomic number

Question 3

Isotopes and relative atomic mass

Answer 3

isotopes are …
different forms of the same element, which have the SAME number of protons but DIFFERENT numbers of neutrons
- relative atomic mass
???

Question 4

history of the periodic table

Answer 4

• chemists in the 1800’s didn’t know about the structure of atoms, but they could measure the relative atomic mass if each element
  when they were put in order of their relative atomic mass, scientists began to notice periodic patterns in the properties of the elements
• Mendeleev, arranged around 50 elements according to their properties and the properties of their compounds to make a table. He left gaps for undiscovered elements.
• these gaps predicted the properties of undiscovered elements

Question 5

the periodic table

Answer 5

• periods - rows in periodic table - are arranged in order of increasing atomic number along each row
• groups - columns of the periodic table - elements in the same group have similar properties - group number = the number of electrons in the outer shell