CH-2
The particles in this are very close together.
What is Solid?
Non-metals that are solids are ___.
What is brittle?
Is melting chocolate a physical change or a chemical change?
Physical change.
A change that can be undone.
What is reversible change?
Heating a solid increases its temperature. What happens to the particles?
They gain energy and move apart.
How many naturally occurring elements are there?
94.
Copper and zinc make ___.
What is brass?
Melting ice is an example of this kind of change.
What is physical change?
This process can be used to separate salt from saltwater.
What is evaporation?
Salt dissolves in water but does not disappear. What happens to the salt particles?
They mix.
Which 3 elements are there in calcium nitrate?
Calcium, Nitrogen, Oxygen.
What is the colour of an acid in universal indicator?
Red/Yellow
In an experiment, when zinc is dropped in sulfuric acid, what gas is given off?
Hydrogen
Why does dissolving salt in water not count as a chemical reaction?
Since it can be reversed.
How can you prove that dissolving salt in water is reversible?
By evaporating the water.
When you observe liquids from eye level, the layer formed is known as ___.
Meniscus
Why are alloys so strong?
Varies.
Gases can change both shape and this.
What is volume?
Give the symbol for Boron.
What is B?
Burning magnesium gives a bright white light. What evidence shows this is a chemical reaction?
Formation of new substance/Release of energy
The symbol for iron.
What is Fe?
Give 8 properties of metals.
Strong, Shiny, Malleable, Ductile, Sonorous, High melting points, Conduct heat and electricity well, Magnetic.
Name 3 signs that a chemical change has happened.
What is colour change / gas produced / heat released / new substance formed / change in pH?
Explain why some chemical symbols, like Cl and Si, have 2 letters.
Varies.
Two substances look identical before and after heating. How could the change still be chemical?
Because particle rearrangement can occur without a visible change.