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Atomic Structure and Chemistry Foundations
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Atomic Structure and Chemistry Foundations
Atomic Structure and Chemistry Foundations
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1
Question
What is the definition of an atom according to the AQA GCSE chemistry content?
Answer
The smallest part of an element that can exist.
2
Question
How does the radius of an atom's nucleus compare to the atom itself?
Answer
The nucleus radius is less than 1/10,000 of the atom's radius, about 1 × 10^{-14} m.
3
Question
What defines an element in chemistry?
Answer
A substance made up of only one type of atom.
4
Question
Why do elements have unique properties?
Answer
Each consists of only one type of atom with specific characteristics.
5
Question
What is a compound and how does it differ from elements?
Answer
A substance containing two or more different elements chemically combined in fixed proportions; unlike elements, it has properties different from its elements.
6
Question
Why do compounds have properties different from their constituent elements?
Answer
Chemical combination alters structure and bonding, changing reactivity and physical traits, like iron oxide vs. iron and oxygen.
7
Question
What characterizes chemical reactions?
Answer
Formation of one or more new substances, often with energy change like temperature increase or decrease.
8
Question
How do you balance a symbol equation step by step?
Answer
1. Count atoms of each type on both sides. 2. Add coefficients to balance unequal atoms, starting with most complex. 3. Recheck all atoms match.
9
Question
What are the key formulas to memorize for balancing equations?
Answer
CO2 (carbon dioxide), H2O (water), O2 (oxygen), H2 (hydrogen), N2 (nitrogen), NH3 (ammonia), HCl (hydrochloric acid), H2SO4 (sulfuric acid).
10
Question
Where are protons and neutrons located in an atom?
Answer
Both in the central nucleus; protons positive, neutrons neutral.
11
Question
Why do electrons have negligible mass compared to protons and neutrons?
Answer
Relative mass ~1/2000; protons and neutrons each mass 1.
12
Question
How do atoms of different elements differ in subatomic particles?
Answer
Different number of protons; same element atoms have identical protons.
13
Question
What are isotopes and how do they relate to atomic mass?
Answer
Atoms of same element (same protons) but different neutrons; explains non-whole relative atomic masses as averages.
14
Question
How does an atom become an ion?
Answer
Gains or loses electrons, creating charged particle; e.g., Be loses 2e- → Be^{2+}.
15
Question
Why does losing electrons make an atom more positive?
Answer
Electrons negative; removing them leaves excess protons' positive charge.
16
Question
How many electrons fit in the first three electron shells?
Answer
First: 2, second: 8, third: 8.
17
Question
How do you determine protons, neutrons, electrons from periodic table notation?
Answer
Atomic number (bottom/small) = protons = electrons (neutral atom); neutrons = mass number (top/large) - protons.
18
Question
For a negative ion like Br^-, how do you calculate electrons?
Answer
Electrons = protons + charge magnitude (negative ion gains electrons).
19
Question
What is relative atomic mass and why are some not whole numbers?
Answer
Average mass of element atoms compared to 1/12 carbon-12; isotopes average yields non-whole like Cl 35.5.
20
Question
How do you calculate relative atomic mass from isotope abundances?
Answer
(Abundance1 × mass1 + abundance2 × mass2 + ...) / 100.
21
Question
What is a mixture and how is it separated from compounds?
Answer
Two or more elements/compounds not chemically combined; separated physically (filtration etc.), unlike compounds needing reactions.
22
Question
Why is filtration used for separating insoluble solids from liquids?
Answer
Solid particles too large to pass filter paper; liquid passes through to flask.
23
Question
How does simple distillation separate solvent from solution?
Answer
Heat evaporates solvent, vapor condenses in condenser back to liquid, leaving solute; keeps liquid.
24
Question
What distinguishes fractional from simple distillation?
Answer
Fractionating column separates liquids by boiling points; lowest BP evaporates first.
25
Question
Why use pencil line in chromatography?
Answer
Pencil insoluble in solvents; doesn't move or interfere with spots.
26
Question
How did Rutherford's experiment disprove plum pudding model?
Answer
Most alpha particles passed through gold foil undeflected (empty space), some deflected, few bounced back (tiny positive nucleus).
27
Question
Why are elements in the same periodic table group similar?
Answer
Same outer shell electrons determine reactivity and properties.
28
Question
How did Mendeleev improve early periodic tables?
Answer
Arranged by properties in columns, left gaps for undiscovered, adjusted atomic weights for patterns.
29
Question
Where are metals and non-metals on the periodic table?
Answer
Metals left of staircase (above Al), non-metals right.
30
Question
Why are noble gases (Group 0) unreactive?
Answer
Full outer electron shell; stable, no tendency to gain/lose/share electrons.