Atomic Structure and Cells
Atomic Structure and Cells
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Atomic Structure and Cells
Open by linking the two ideas: atoms are the tiny particles that make up matter, and cells are the basic units of living things. This lesson brings together chemistry and biology through structure and function.
Our learning goal
I can describe the structure of atoms and cells, and use diagrams and data to identify their main parts and functions.
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One word or phrase you link with atoms or cells
Use this as a prior-knowledge activation after the learning goal. Invite a mix of chemistry and biology words, then pick out any correct prior ideas and any misconceptions to revisit later.
What do you already know?
Matter is made of tiny particles.
Living things are made of cells.
Atoms are far too small to see with the naked eye.
Cells also need tiny structures inside them to work.
In this lesson, we build from these basic ideas to named parts and their jobs.
The teacher requested a warm-up quiz, but this pass produces content slides only. Use this slide as a retrieval bridge by briefly revisiting prior knowledge before teaching new content.
What is an atom?
An atom is the basic particle of an element.
Atoms are extremely small.
Each atom has a centre called the nucleus.
Smaller particles are found inside the atom.
Different elements have different atoms.
Keep the model simple and age-appropriate. Avoid quantum detail; focus on the nucleus and electrons around it.
The three subatomic particles
Protons are in the nucleus.
Neutrons are in the nucleus.
Electrons move around the nucleus.
The nucleus is small but contains most of the atom's mass.
Emphasise location clearly: protons and neutrons in the nucleus, electrons in shells or energy levels around the nucleus.
Charge and relative mass
Proton - 1
Neutron - 1
Electron - very small, about 1/1836
Relative mass
Charge
Proton - +1
Neutron - 0
Electron - -1
Students often confuse charge and mass. Stress that protons and neutrons have similar mass, while electrons have a very small mass.
A simple atom summary
Nucleus: contains protons and neutrons
Outside the nucleus: electrons
Protons = positive
Neutrons = no charge
Electrons = negative
In a neutral atom, the number of protons equals the number of electrons.
This is a key checkpoint idea. Many later examples depend on students remembering that neutral atoms have equal protons and electrons.
Which particle is found outside the nucleus?
Neutron
Electron
Proton
Nucleus
Checks the key location idea from slides 3–6. A common error is mixing up electrons with neutrons or protons.
Atom summary
In an atom, the nucleus contains protons and neutrons. Electrons move around the nucleus. A proton has a positive charge.
Focus students on location and charge, not just naming the particles.
Using the periodic table
The periodic table helps us identify particles in an atom.
Atomic number = number of protons
In a neutral atom, this also gives the number of electrons
Mass number = protons + neutrons
Use one element box on the board and point out where the atomic number is found. Keep to simple atoms only, as requested.
How to find each particle
Use these rules:
Protons = atomic number
Electrons = atomic number in a neutral atom
Neutrons = mass number - atomic number
Example pattern:
Atomic number 8, mass number 16
→ protons 8, electrons 8, neutrons 8
Model the subtraction slowly. Students often try to subtract the wrong way round.
Worked example: sodium
For sodium:
Atomic number = 11
Mass number = 23
Protons = 11
Electrons = 11
Neutrons = 23 - 11 = 12
So a sodium atom has 11 protons, 12 neutrons and 11 electrons.
You may also mention that students will often see sodium written as Na. Keep the focus on counting particles, not electron arrangement.
More atom examples
Hydrogen: 1 proton, 0 neutrons, 1 electron
Carbon: 6 protons, 6 neutrons, 6 electrons
Oxygen: 8 protons, 8 neutrons, 8 electrons
Each example is a neutral atom.
These examples are useful because they show that neutron number is not always the same as proton number in every atom, but in simple classroom examples it often can be.
Reading atom diagrams
Simple atom diagrams usually show:
a central nucleus
protons and neutrons inside the nucleus
electrons around the outside
labels or numbers to show each particle
The diagram is a model, not a real picture of an atom.
Important misconception: students may think diagrams show exact size and distance. Clarify that they are simplified models.
Atoms: exam-style summary
When describing an atom, include:
the three subatomic particles
where each particle is found
the charge of each particle
the relative mass of each particle
how atomic number and mass number help you work out the numbers
This slide prepares students for short-answer and exam-style responses without presenting activity questions.
A neutral atom has 9 protons. How many electrons does it have?
18
9
10
0
Tests the rule that neutral atoms have equal numbers of protons and electrons.
Using atomic and mass number
The atomic number tells us the number of protons. In a neutral atom, this also gives the number of electrons. The mass number is the total of protons and neutrons, so neutrons can be found by subtraction.
Echoes the exact rules taught on slides 7–12. 'Subtraction' here means mass number minus atomic number.
Why is an atom diagram called a model?
Expected elements: the diagram is a model, not a real picture; the nucleus is in the centre; protons and neutrons are in the nucleus; electrons are around the outside; sizes and distances are not shown exactly.
What is a cell?
A cell is the basic unit of life.
All living things are made of cells.
Cells have structures inside them called organelles.
Each organelle has a function.
Plant and animal cells have many features in common.
Shift clearly from chemistry to biology: atoms build substances, and living things are made from cells.
Animal cell structure
An animal cell usually contains:
nucleus
cytoplasm
cell membrane
mitochondria
ribosomes
These organelles help the cell stay alive and do its job.
Keep the labelled diagram simple and uncluttered so students can identify the core organelles.
Functions in an animal cell
Nucleus - controls the cell's activities
Cytoplasm - where many chemical reactions happen
Cell membrane - controls what enters and leaves the cell
Mitochondria - where aerobic respiration releases energy
Ribosomes - where proteins are made
Students may say the nucleus is the 'brain' of the cell. You can accept this as a simple memory aid, but keep the scientific phrasing as 'controls the cell's activities'.
Which organelle controls the cell's activities?
Cytoplasm
Mitochondria
Nucleus
Ribosomes
Checks one of the core organelle-function pairs from the animal cell block.
Animal cell functions
In an animal cell, the cytoplasm is where many chemical reactions happen. The cell membrane controls what enters and leaves the cell. Mitochondria release energy, and ribosomes make proteins.
All blanks are load-bearing function terms already taught on slides 14–15.
Plant cell structure
Plant cells have the same parts as animal cells, but they also have:
cell wall
chloroplasts
permanent vacuole
Emphasise 'also have' rather than implying plant cells lack nucleus, cytoplasm or membrane.
Functions in a plant cell
Cell wall - strengthens and supports the cell
Chloroplasts - contain chlorophyll for photosynthesis
Permanent vacuole - contains cell sap and helps keep the cell firm
Plant cells still have a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes too.
Students often confuse the cell wall and cell membrane. Stress that both are present in plant cells, but they do different jobs.
Plant cells and animal cells
Nucleus
Cytoplasm
Cell membrane
Mitochondria
Ribosomes
Only plant cells have
Both have
Cell wall
Chloroplasts
Permanent vacuole
This acts as the requested comparison table in a slide-friendly format.
How the diagrams differ
Plant cells are often drawn with a more regular shape.
Animal cells are often drawn as more rounded or irregular.
The cell wall gives extra support to plant cells.
Chloroplasts are only shown in plant cells.
Remind students that real cells can vary in shape; these are simple textbook models.
Linking organelles to functions
A good way to learn organelles is to match each part to its job:
control → nucleus
chemical reactions → cytoplasm
entry and exit → cell membrane
energy release → mitochondria
protein making → ribosomes
support → cell wall
photosynthesis → chloroplasts
cell sap storage → permanent vacuole
The teacher requested matching questions, but this pass avoids activity slides. This content supports later matching tasks.
Cells: exam-style summary
When comparing plant and animal cells, make sure you:
name shared organelles
name organelles only found in plant cells
give the correct function for each organelle
use labelled diagrams accurately
use the word organelle correctly
Encourage precise vocabulary. Students often write 'part' instead of 'organelle'; both may communicate meaning, but scientific language is better.
Which structure is found only in plant cells?
Nucleus
Cell membrane
Mitochondria
Chloroplasts
Checks the plant-only idea and helps separate shared organelles from plant-specific ones.
Comparing plant and animal cells
Plant and animal cells both have a nucleus, cytoplasm and cell membrane. Only plant cells have a cell wall and chloroplasts. A permanent vacuole helps keep the cell firm.
Targets the comparison table and the plant-cell function summary from slides 16–21.
Which part of today's learning now feels clearest?
Atoms
Using the periodic table
Animal cells
Plant cells
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What is one thing you will remember from this lesson?
Invite short reflective answers such as a rule, organelle, comparison, or worked-example method that stuck in memory.
Which part of the lesson felt hardest today?
Use responses to identify what needs reteaching next lesson. Likely answers: neutrons from mass number, atom models, plant-only organelles, or organelle functions.
Glossary
atom - the basic particle of an element
nucleus - the centre of an atom; in cells, the organelle that controls activities
proton - a positively charged particle in the nucleus of an atom
neutron - a particle with no charge in the nucleus of an atom
electron - a negatively charged particle moving around the nucleus
atomic number - the number of protons in an atom
mass number - the total number of protons and neutrons in an atom
Note that nucleus has two meanings in this lesson: atomic nucleus and cell nucleus. Flag this clearly to avoid confusion.
Glossary
cell - the basic unit of life
organelle - a structure inside a cell that carries out a function
cytoplasm - the jelly-like material where many reactions happen
cell membrane - the barrier that controls what enters and leaves the cell
mitochondria - organelles where aerobic respiration releases energy
ribosomes - organelles where proteins are made
cell wall - a strong outer layer that supports plant cells
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Glossary
chloroplasts - organelles containing chlorophyll for photosynthesis
permanent vacuole - a space containing cell sap that helps keep a plant cell firm
neutral atom - an atom with equal numbers of protons and electrons
relative mass - the mass of a particle compared with another particle
charge - whether a particle is positive, negative or has no charge
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