Chemistry might seem daunting, but it's actually all around you...
Chemistry110 views·Updated 2 Sept 2026·4 pagesUnderstanding Chemistry: Atoms, Molecules, Compounds, and Mixtures
Corah@corahbretton
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1
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The Basics of Matter
Everything you see is made of atoms - think of them as nature's building blocks. When atoms team up, they form molecules, and this is where chemistry gets interesting.
Compounds are formed when two or more different elements join forces chemically - like sodium and chlorine creating table salt. Mixtures, on the other hand, are just substances hanging out together without any chemical commitment, like oil and water.
Here's a golden rule that'll save you in exams: conservation of mass means the mass of what you start with always equals the mass of what you end up with. No atoms disappear - they just rearrange themselves.
Pro tip: When balancing equations, count atoms on both sides like you're checking your maths - they should always match up perfectly.
2
of 4
Inside the Atom
Atoms are incredibly tiny - about 1 × 10⁻¹⁰ metres across, which means you could fit millions across the width of a human hair. The nucleus at the centre is 10,000 times smaller than the whole atom, yet contains nearly all its mass.
Every atom has an atomic number (number of protons) that determines what element it is. The mass number tells you the total protons plus neutrons. Think of protons as an element's ID card - hydrogen always has 1, helium always has 2.
Isotopes are like identical twins with different weights - same element, same number of protons, but different numbers of neutrons. Carbon-12 and carbon-13 are perfect examples, both carbon but with slightly different masses.
Remember: The number of protons never changes for an element - that's what makes carbon always carbon and oxygen always oxygen.
3
of 4
Chemical Bonding
Compounds form when elements get together and actually bond chemically - it's like they're getting married rather than just dating. This happens through electrons being shared, given, or taken between atoms.
Ionic bonding occurs between metals and non-metals. The metal loses electrons (becoming positive), whilst the non-metal gains them (becoming negative). These opposite charges attract like magnets - think sodium chloride or magnesium oxide.
Covalent bonding happens when non-metals share electrons, creating molecules. Water, carbon monoxide, and nitrogen chloride are classic examples where atoms team up by sharing rather than transferring electrons.
Quick check: Metal + non-metal = ionic bonding, whilst non-metal + non-metal = covalent bonding.
4
of 4
Separation Techniques and Atomic History
Scientists use different tricks to separate mixtures: crystallisation for getting solids from solutions, distillation for separating liquids with different boiling points, and chromatography for substances that dissolve differently.
The story of atomic discovery is brilliant. John Dalton imagined atoms as tiny, indivisible spheres. J.J. Thompson suggested the plum pudding model - a positive ball with electrons stuck in it like raisins.
Rutherford's alpha scattering experiment changed everything. By firing particles at gold foil, he discovered that atoms are mostly empty space with a tiny, dense nucleus. Niels Bohr then proposed that electrons orbit in specific energy levels or shells.
Fun fact: Most alpha particles went straight through the gold foil, proving atoms are mostly empty space - you're basically made of nothing!
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Chemistry110 views·Updated 2 Sept 2026·4 pagesUnderstanding Chemistry: Atoms, Molecules, Compounds, and Mixtures
Corah@corahbretton
Chemistry might seem daunting, but it's actually all around you - from the water you drink to the air you breathe. This chapter covers the fundamental building blocks of matter and how scientists figured out what atoms really look like...
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The Basics of Matter
Everything you see is made of atoms - think of them as nature's building blocks. When atoms team up, they form molecules, and this is where chemistry gets interesting.
Compounds are formed when two or more different elements join forces chemically - like sodium and chlorine creating table salt. Mixtures, on the other hand, are just substances hanging out together without any chemical commitment, like oil and water.
Here's a golden rule that'll save you in exams: conservation of mass means the mass of what you start with always equals the mass of what you end up with. No atoms disappear - they just rearrange themselves.
Pro tip: When balancing equations, count atoms on both sides like you're checking your maths - they should always match up perfectly.
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Inside the Atom
Atoms are incredibly tiny - about 1 × 10⁻¹⁰ metres across, which means you could fit millions across the width of a human hair. The nucleus at the centre is 10,000 times smaller than the whole atom, yet contains nearly all its mass.
Every atom has an atomic number (number of protons) that determines what element it is. The mass number tells you the total protons plus neutrons. Think of protons as an element's ID card - hydrogen always has 1, helium always has 2.
Isotopes are like identical twins with different weights - same element, same number of protons, but different numbers of neutrons. Carbon-12 and carbon-13 are perfect examples, both carbon but with slightly different masses.
Remember: The number of protons never changes for an element - that's what makes carbon always carbon and oxygen always oxygen.
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Chemical Bonding
Compounds form when elements get together and actually bond chemically - it's like they're getting married rather than just dating. This happens through electrons being shared, given, or taken between atoms.
Ionic bonding occurs between metals and non-metals. The metal loses electrons (becoming positive), whilst the non-metal gains them (becoming negative). These opposite charges attract like magnets - think sodium chloride or magnesium oxide.
Covalent bonding happens when non-metals share electrons, creating molecules. Water, carbon monoxide, and nitrogen chloride are classic examples where atoms team up by sharing rather than transferring electrons.
Quick check: Metal + non-metal = ionic bonding, whilst non-metal + non-metal = covalent bonding.
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Separation Techniques and Atomic History
Scientists use different tricks to separate mixtures: crystallisation for getting solids from solutions, distillation for separating liquids with different boiling points, and chromatography for substances that dissolve differently.
The story of atomic discovery is brilliant. John Dalton imagined atoms as tiny, indivisible spheres. J.J. Thompson suggested the plum pudding model - a positive ball with electrons stuck in it like raisins.
Rutherford's alpha scattering experiment changed everything. By firing particles at gold foil, he discovered that atoms are mostly empty space with a tiny, dense nucleus. Niels Bohr then proposed that electrons orbit in specific energy levels or shells.
Fun fact: Most alpha particles went straight through the gold foil, proving atoms are mostly empty space - you're basically made of nothing!
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