Site of Respiration

 The Mitochondrion is the site of respiration. Is this an ancient bacterium that invaded another in an example of symbiosis that created a new type of organism? DNA Evidence? Mitochondria self-replicate.

Calculating Depreciation

 ​In Business, depreciation refers to the gradual decrease in value of an asset over time due to factors like wear and tear or obsolescence, and it's a key accounting concept used to allocate the cost of an asset over its useful life. 

How a hard disk works

 Taking a hard disk to bits so that the students could see how a hard disk works.

Displacement reactions

Using displacement reactions, comparing the reactivities of three different metals with their sulfates—Copper, Iron, and Zinc—to find out which is the most reactive and which is the least.

Gay Lussac's Law

 Constant volume: Increasing the Temperature increases the pressure—Gay Lussac's Law. It is so much easier and more accurate to use a @pascoscientific wireless pressure sensor than a Bordon Gauge.

Cards and Probability

Many questions in Maths Papers look at the probability of selecting a card but many students don't play cards except perhaps on a computer games and don't know the names, values or suits.

 

The Laplace rail demonstration

The Laplace rail demonstration is a piece of scientific equipment used to demonstrate the force exerted on a current-carrying conductor in a magnetic field, illustrating the motor effect and fundamental electromagnetic principles. 

Spirogyra

 Life is beginning in the pond and it is a good time to look at spirogyra and get the students to try and record what they actually see rather than what they think they see.

Food Rewards

 A-Level Psychology: We are what we eat. Does what our mother ate when pregnant affect what we like to eat and does letting kids have food rewards help them in the long term?

Analog Computers

 A Level Computing. Looking at different types of computers, including some analog computers.  Unlike digital computers that use discrete data, they use continuously variable physical quantities, like voltage or mechanical motion, to model and solve problems.

What’s So Special About the Dative Covalent Bond?

A-Level Chemistry: What is the difference between a normal covalent bond and a dative covalent bond. Although the electrons are shown differently in a diagram, there is no difference between them in reality, and in reactions, any of the bonds might be broken.

What’s So Special About the Dative Covalent Bond?

When you first learn about covalent bonding in GCSE Chemistry, it's pretty straightforward: two atoms share a pair of electrons to fill up their outer shells and become more stable. But at A-level, things get juicier. You’re introduced to a slightly more complex version of the covalent bond—the dative covalent bond, also known as a coordinate bond.

So, what is this mysterious bond, and how is it different from the good old ordinary covalent bond? Let’s break it down.

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🧪 The Ordinary Covalent Bond

In a normal covalent bond, each atom provides one electron to the shared pair. Think of it like two friends splitting the bill at a café: one pays for the coffee, the other for the cake. Fair and square.

For example:

• In a molecule of hydrogen (H₂), each hydrogen atom has one electron. They come together and share, forming a bond with a pair of electrons—one from each atom.
• In oxygen gas (O₂), each oxygen shares two electrons, forming a double covalent bond.

This sharing allows both atoms to achieve a stable electron configuration (often the noble gas configuration).

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🎯 Enter the Dative Covalent Bond (Coordinate Bond)

Now imagine a situation where one atom provides both electrons for the bond. This is a dative covalent bond.

It’s like one friend paying for the entire meal while the other friend just turns up and enjoys the food. Generous? Perhaps. But both still get a good time out of it—just like both atoms benefit from the bond.

💬 Key Definition:

A dative covalent bond is a type of covalent bond in which both electrons in the shared pair come from the same atom.

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🌟 Examples of Dative Covalent Bonds

1. Ammonium Ion (NH₄⁺)

• Ammonia (NH₃) has a lone pair of electrons on the nitrogen atom.
• A hydrogen ion (H⁺), which has no electrons, comes along.
• Nitrogen donates both electrons from its lone pair to form a bond with the H⁺.
• The result? An ammonium ion with four N–H bonds—one of which is dative.

✏️ We usually show the dative bond with an arrow pointing from the donor atom:

![N → H⁺]

2. Aluminium Chloride (Al₂Cl₆)

• In its dimer form, one aluminium atom (electron-deficient) accepts a lone pair from a chloride ion.
• This donation creates a dative bond from Cl to Al.

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🧠 So… What’s the Difference Again?

Feature	Ordinary Covalent Bond	Dative Covalent Bond
Electron Contribution	One electron from each atom	Both electrons from one atom
Still Covalent?	✅ Yes	✅ Yes
Representation	Single line (–)	Arrow (→), from donor to acceptor
Example	H₂, O₂, CH₄	NH₄⁺, Al₂Cl₆, H₃O⁺

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🎓 Why Does It Matter?

At A-level, understanding who's donating what in a bond is essential—especially when it comes to:

• Drawing correct dot-and-cross diagrams
• Naming ions and compounds
• Predicting shapes of molecules (VSEPR theory)
• Understanding acid-base behaviour (in Bronsted-Lowry and Lewis terms)

It also appears in:

• Transition metal complexes
• Biological systems (e.g. haemoglobin binding O₂)

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🧪 Summary

Dative covalent bonds are just a special case of covalent bonding, where one atom does all the sharing. It’s still covalent, it still involves shared electrons, but the ownership history of those electrons tells us a lot about chemical reactivity and structure.

Next time you see a lone pair looking for something to bond with—ask yourself: “Could this be a dative bond moment?”

 

Firmware up to date

 Some of the regular jobs using the @pascoscientific sensors is the keep all the firmware up to date and charge or change the batteries so the sensors are ready for action.

Different sided dice

 Changing the probabilities: Instead of the usual 1/6, we looked at 3—to 9-sided dice to see how the probabilities changed. It was also interesting to see the shapes that these dice made.

Steam Engine

 Energy transfers using a steam engine. There is nothing like having a steam engine in the classroom. The interest level goes up and so does the enthusiasm to control the engine and make hammers work and polishers polish.

Plating results

Investigating the effects of Mint and Garlic on the growth of bacteria. The results were not as good as we had hoped. With different concentrations only the most concentrated had any effect on the development of bacteria, suggesting that these bacterial agents are not that effective.

 

Parliamentary Makeup

 A-Level Sociology. Does Parliament reflect the social makeup of the population it represents in 2025? Book stats are out of date. There is a 60:40 split in men to women. Nearly 24% of MPs went to independent schools and 85% are University graduates. How do you feel about the social makeup?

BSOD

 What is the Blue Screen of Death? What does it mean, and how can we recover from it? A-level computing students find out how to fix the machine so it works again.

Rusting

 Three test tubes after a few weeks. The staple in water and air had all but rusted away, the one in air but no water was untouched, and the one with water and no air because of the oil had only a joint of rusting. The students had to explain why.

Elastic Collisions

Using the magnets on two smartcarts to demonstrate elastic collisions. Using the @pascoscientific Capstone, the before and after graphs can quickly be compared to show the change in momentum and that it is conserved.

 

Practical Maths

 Practical Math. It is okay to do some Math problems, but sometimes it is nice to see and understand the Physics behind them. What is an elastic collision? Watching the Newtons cradle gave an idea about what the Mechanics problem was all about.

Goldleaf Electroscope

 The Goldleaf electroscope is such a simple piece of equipment yet one of the most useful. I have tried this with dutch metal but only with gold leaf does it work exceptionally well. With a decent UV light is demonstrates the photoelectric effect well.

Investigating mint and garlic

 Microbiology at A Level: Investigating the effect of Mint and garlic extracts on bacteria cultures. Which one is the most effective and why? Are there any other plant extracts that work like this? So, in addition, we are investigating some other herbs to see if they kill bacteria too.

Hardness of the Alkali Metals

Investigating the reactivity and properties of the Alkali Metals. Cutting each of the metals in turn with a sharp scalpel. Lithium was the hardest and stayed shiny the longest, and Potassium was the easiest to cut and tarnished as it was cut.

 

Magnetic Fields

 Using the @pascoscientific magnetic field probe along with the smartcart or a rotation sensor to get a reading of the magnetic field strength as the probe moves further into different magnetic fields

Globaslisation

 A level Business Studies—Globalisation The Earth is becoming smaller, and it is often cheaper to move manufacturing items around the world to be constructed than to do them in the same country. Maybe Trump will change the way the world works.

Youngs doble slit experiment

​Exploring wave-particle duality with my A-level Physics students. Doing experiments demonstrating light behaving like a wave and also acting as particles – it’s hurts the brain how the universe plays by both rules!

 

Infection Games

 Playing an infection game to simulate the growth of an infection in a population, and then repeating the game using vaccination to see the effect this has on the rate of an infection. 

Flowcharts

 ​Teaching flowcharting is key to writing better computer programs!  It helps the students visualize logic, simplifies problem-solving, and boosts code clarity. Perfect for beginners to understand the flow and structure before diving into code.