Atomic Structure & Electron Configuration
Name the three subatomic particles and their charges
Protons (+), neutrons (no charge), and electrons (-).
What charge do cations and anions carry, respectively?
Positive and Negative
What makes an isotope unstable?
The nucleus is decaying/breaking down due to different numbers of neutrons
What is the definition of a Half-life?
The time taken for half the radioactive substance to decay
What is one difference between ionic and covalent bonds?
Covalent - share electrons, metal + metal
An atom has the electron configuration 2,8,8,1. What element is it?
Potassium
What happens to Lithium (Li+) when it forms an ion?
Lose an electron
Explain one difference between isotopes?
Number of Neutron
or
Mass Number
Which radioactive particle almost travels at the speed of light?
Beta
Would Aluminum & Oxygen create an ionic bond or a covalent bond?
Ionic Bond
What is the mass for the three subatomic particles?
Protons: 1 amu
Neutrons: 1 amu
Electrons: 0 amu
Explain the difference between a cation and anion?
Cation = Atom that has lost electrons
Anion = Atom has gained electrons
What can beta be stopped by?
Thin pieces of plastic, wood or aluminium
A radioactive isotope has a half-life of 5 years. If you start with 80 g, how much remains after 15 years?
10 g
Explain why sodium reacts strongly with chlorine but neon does not react.
Sodium = -1 Valence Electron
Chlorine = +1 Valence Electron
Neon already has a full outer shell, making it stable and unreactive.
An atom has 17 protons and 18 neutrons. How many electrons does it have on its valence shell and is it a cation or anion?
7, anion
An atom forms a 3⁻ ion. How many valence electrons did it originally have?
5
If someone is exposed to Gamma radiation, what could they wear to prevent it from penetrating their skin?
A sample decreases from 200 g to 25 g. How many half-lives have passed?
3 half-lives
Zero/No charge.
Compounds are electrically neutral overall as they both fulfil their valence shells
If an unknown atom has 23 electrons, what is its electron configuration?
2, 8, 11, 2
Magnesium forms Mg²⁺ and oxygen forms O²⁻. Explain why the formula of magnesium oxide is MgO and not Mg₂O₂ or Mg₂O?
Mg²⁺ and O²⁻ have equal charges and are opposite signs, so one magnesium ion balances one oxide ion. MgO is electrically neutral, while Mg₂O or Mg₂O₂ would not be the simplest ratio of ions.
What does Thorium-234 become when it releases beta radiation?
Protactinium-234
A radioactive sample has 6g remaining after 5 half-lives. What was the original mass of the sample?
192g
Draw the bond for CaF2 and name the type of bond it shares.
Ionic Bond