Elements, Mixtures and Compounds Flashcards
When do Chemical changes occur?
When Chemical reactions between two elements happen, creating a new substance. They involve the creation of compounds
What are Physical changes?
In a physical change, no substances are formed, instead, a change of state occurs or diffusion.
What elements are in:
1Plastic
2Water
3Car
4Flower
1Hydrogen, Carbon
2Oxygen, Hydrogen
3Alluiminium, Iron, Silicon, Boron, Oxygen
4Oxygen, Hydrogen, Nitrogen, Carbon
What is a molecule?
They are made when two atoms chemically combine. If atoms are from different elements, they create a compound. Helium particles are not molecules. Hydrogen, nitrogen and oxygen’s are.
Atoms/Elements are…
Atom is the smallest particle. Found in Elements.
Elements are made of only one type of atom and cannot be split through chemical methods, though they can through electrolysis. There are 118
Periodic Table
Columns = groups - link elements with similar properties
Hidrogen
H, A NM
Lithium
Li, a metal
Helium
He, a NM
Beryllium
Be, a metal
Boron
B, a metal
Carbon
C, a nm
Nitrogen
N, a nm
Oxygen
O, a nm
Fluorine
F, a nm
Neon
Ne, a nm
Sodium
Na, a metal
Magnesium
Mg, a metal
Aluminium
Al, a metal
Silicon
Si, a nm
Phosphorus
P, a nm
Sulfur
S, a nm
Chlorine
Cl, a nm
Argon
Ar, a nm
Potassium
K, a metal
Calcium
Ca, a metal
1 iron/ 2 sulphur/ 3 iron sulphide is…
1brown grey, is magnetic and forms hydrogen with hydrochloric acid
2yellow, isn’t magnetic
3dark black, isn’t magnetic, Hydrogen sulfate formed with hydrochloric acid
When burnt, magnesium
Changes from wire to powder as it reacts with oxygen
Signs of a Chemical Reaction
*Light is given off
*change of colour
*heat is given off
* gas is given off
*smell is given off
*sound is given off
Iron chloride, potassium
Bloody red
Copper Sulphate/ammonia solution
Dark blue
Coper Sulphate/zinc
Black
Barium nitrate/sodium sulphate
Opaque white
Iron sulphate/sodium hydroxide
Gold
Barium nitrate/sodium hydroxide
Opaque purple
Silver nitrate/iron sulphate
Extremely opaque
Ammonia conadate/hydrochloric acid and zinc
White
Why can’t chemical changes easily be reversed
As atoms from different elements have bonded, meaning that they have a different composition to before. For example, when magnesium is burnt, it turns into a powder, which can’t be easily a wire again
Why doesn’t mass change in chemical/physical changes?
As no atoms are added or taken away throughout the change. The new substance created in chemical reactions is composed of the reactants’ atoms.
