Atoms & Structure
What are the three main subatomic particles?
Protons, neutrons and electrons
Which element has the symbol Na?
Sodium
How many electrons fit in the first shell?
2
What is a cation?
A positively charged ion
What is the pH of a neutral solution like pure water?
7
Where are protons and neutrons found?
Nucleus
Which group is the noble gases?
18
Sodium has 11 electrons. What is its electron configuration?
2,8,1
Sodium forms which ion: Na⁺ or Na⁻?
Na⁺
What type of ions are present in acids?
Hydrogen ions (H⁺ / H₃O⁺)
What does the atomic number tell you?
The number of protons (and also electrons in a neutral atom).
Why do elements in the same group have similar properties?
They have the same number of electrons in their outer shell
An atom has 17 electrons. How many energy shells does this atom have?
3
Why do non-metals form negative ions?
They gain electrons to fill their outer shell
What happens to the pH when you dilute a base with water?
It decreases (less basic)
What happens if the number of protons in an atom changes?
It becomes a different element
Which has more in common: Na and K, or Na and Cl?
Na and K – both in Group 1
Why are noble gases unreactive?
They have full outer electron shells
Oxygen has 8 protons. How many electrons does O²⁻ have, and why?
10 electrons (8 normally + 2 extra gained to make the ion stable)
Neutralisation reactions produce what two products?
Salt and water
Why isn’t an element’s atomic mass exactly the sum of its protons and neutrons, and why does it often include a small decimal?
It’s an average of all atoms of that element, which can have different numbers of neutrons.
Why do Group 1 metals get more reactive as you go down the group?
The outer electron is further from the nucleus, so it’s lost more easily
Why do metals produce light when heated in a flame?
Adding heat energy moves electrons up a shell, and when they fall back down, they release light.
What is the name of the ion with the formula NO₃⁻?
Nitrate
What is the name of the ion formed when H⁺ combines with water?
Hydronium ion (H₃O⁺)