Furthermore, the element symbol (Cu) can actually represent billions of particles in a giant structure, rather than one individual atom. Emphasise how, for example, individual copper atoms have no colour, but billions of them joined together make a lustrous red metal. Precipitation of lead iodide (golden rain) (rsc.li/2nfehuM)Ī common misconception is that atoms share the properties of the bulk material (rsc.li/2KxjYNR). Iron and sulfur reaction (rsc.li/2vHlEz4)Įxtracting iron from breakfast cereal (rsc.li/2OOeYYH)Ī solid–solid reaction between lead nitrate and potassium iodide (rsc.li/2nhAUPm) Sodium and chlorine reaction (rsc.li/2LUqm7o)ĭehydration of sucrose (creates a carbon tower) (rsc.li/2vJev15) Practicals or demostrations that show elements or compounds forming Demonstration or practical Precipitation of lead iodide (golden rain) Where did the yellow substance come from? Would this have been possible if it had reacted to form a compound with the cereal?Ī solid–solid reaction between lead nitrate and potassium iodideĪ new substance formed from the reaction between two compounds Why couldn’t you see the iron in the cereal? The iron was extracted using a magnet. Why can you separate iron from sulfur before it has reacted, but not afterwards?Īn unreacted element extracted from a substance Two elements reacting together to form a compound, with observably different properties to the original elements * In reality, oxidation follows the first reaction, complicating matters, but this can be overlooked at this stage. Which element can you observe at the end of the reaction?* Where are the hydrogen and oxygen atoms now? Sucrose contains carbon, hydrogen and oxygen atoms. Where are the sodium atoms at the end of the reaction?ĭehydration of sucrose (creates a carbon tower)Ī compound reacting and ‘losing’ atoms, leaving a constituent element visible Two elements reacting together to form a compound Practicals and demonstrations that show elements or compounds forming Demonstration or practical There’s tacit knowledge about chemical substances students only gain by seeing and touching, so have a box of samples for students to explore. Molecules are substances formed when two or more atoms are chemically joined (bonded).Īs science teachers, we are fortunate we can demonstrate key ideas in front of students’ eyes.A compound has chemical properties different from the properties of the elements it contains.A compound has a definite chemical composition and hence specific formula.A compound is a substance formed from two or more elements chemically joined (bonded) together.An atom is the smallest particle of an element that can take part in chemical reactions.An element is a substance that cannot be chemically decomposed into simpler substances. What do students need to know about elements and compounds? The elements are fundamental to everything we do as chemists, and their symbols act as our common international language. How can it be that we are made of the same stuff as stars? It can be hard to conceive that everything around us, and within us, is made up of just 100 or so elements.
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