end of year exams Flashcards
(64 cards)
Atomic number
The number of protons in an atom.
Example: Carbon has an atomic number of 6 (6 protons).
Mass Number
The sum of protons and neutrons in an atom.
Example: Carbon-12 has a mass number of 12 (6 protons + 6 neutrons).
Why do Alkali metals react violently with water?
Alkali metals have one electron in their outer shell, which they want to lose to become stable, making them highly reactive with water.
Noble gases
Gases that are inert because their outer electron shells are full.
Example: Helium (He), Neon (Ne), Argon (Ar).
Properties of Metals
Metals conduct heat and electricity and are malleable (can be shaped into different forms without breaking).
Properties of Non-Metals
Non-metals do not conduct heat or electricity well and are generally brittle.
How do you find out what element something is if you’re given the number of protons?
Use the atomic number (which equals the number of protons) to find its place on the periodic table.
Why are alkali metals reactive with water?
Because they have 1 electron on their outer shell and want to lose it to become stable.
How does the reactivity of alkali metals change as you go down the group?
Reactivity increases because the outer electron is further from the nucleus and easier to lose.
Why are noble gases unreactive?
Their outer shells are full, so they don’t need to gain or lose electrons.
How are metals and non-metals different in terms of conduction?
Metals conduct heat and electricity well, non-metals generally do not.
What do the periods and groups in the periodic table represent?
Periods = number of shells; Groups = number of electrons in the outer shell.
What is the name of Group 7 on the periodic table?
Halogens: They have 7 electrons on their outer shell and are very reactive
What makes noble gases unique in terms of reactivity?
Noble gases (Group 0 or 8) have full outer shells, making them non-reactive.
Why are metals good conductors of electricity?
Because they have delocalised (free) electrons that can move and carry charge.
What happens to a substance with a higher boiling point during distillation?
It stays in the flask while the lower boiling point substance evaporates first.
What’s the difference between evaporation and crystallisation?
Evaporation: Removes solvent quickly using heat; might damage crystals.
Crystallisation: Solvent is removed slowly by cooling → forms pure, undamaged crystals.
What method would you use to separate ink colours in a pen?
Chromatography — separates soluble substances based on how they travel on paper.
What method is used to separate salt from saltwater?
Evaporation to get salt
Simple distillation to get pure water
Which method separates an insoluble solid from a liquid?
Filtration
What are the main greenhouse gases?
Carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and water vapor (H2O).
What is the process of global dimming?
Global dimming occurs when particulates from pollution, such as sulfur dioxide, block sunlight, leading to a cooling effect on the Earth’s surface.
How do fossil fuels contribute to global warming?
Burning fossil fuels releases carbon dioxide and other greenhouse gases into the atmosphere, which trap heat and contribute to global warming.
Why does deforestation increase carbon dioxide levels in the atmosphere?
Trees absorb carbon dioxide, so when forests are cut down, the stored CO2 is released back into the atmosphere, increasing greenhouse gases.
