Atoms & Elements
What is the smallest particle of an element that retains its properties?
An atom.
What do we call a substance made from two or more elements chemically joined together?
A compound.
Melting ice is an example of what type of change?
A physical change.
A chemical reaction produces what?
One or more new substances.
What state of matter is steam?
Gas.
What is an element?
A pure substance made of only one type of atom.
What compound is formed when hydrogen and oxygen combine?
Water (H₂O).
During a physical change, is a new substance formed?
No
Name one sign that a chemical reaction has occurred.
Colour change, gas production, temperature change, light, or precipitate formation.
What gas makes soft drink fizzy?
Carbon dioxide.
Name the element represented by the symbol Mg
Magnesium
Is carbon dioxide an element or a compound?
A compound
Name one common physical change.
Melting, freezing, boiling, cutting, crushing, etc.
Why is burning wood a chemical change?
New substances such as ash, smoke and gases are formed.
What element gives balloons their floating ability?
Helium.
What part of an atom has a positive charge?
The proton.
How many compounds are in NaCl
One
Why is dissolving sugar in water considered a physical change?
Because no new substance is formed.
Is cooking an egg a physical or chemical change?
A chemical change.
What element is found in pencils but not actually lead?
Carbon (graphite).
Is gold (Au) an element or a compound?
Element
How many different elements are present in calcium carbonate (CaCO₃)?
Three.
What process changes a gas directly into a liquid?
Condensation.
Which is stronger evidence of a chemical reaction: a change of state or the formation of a gas?
Formation of a gas.
Why do bananas turn brown after being peeled?
Oxidation.