Mixtures
What is the difference between pure substances and mixtures?
TRUE OR FALSE: Heating can cause physical changes in matter, but cooling can't.
FALSE- both heating AND cooling can cause physical changes in matter.
TRUE OR FALSE: Chemical changes are reversible.
What two types of electric charges exist?
POSITIVE charges and NEGATIVE charges
TRUE OR FALSE: Magnets are objects that REPEL other objects made of magnetic materials.
FALSE- Magnets are objects that ATTRACT other objects made of magnetic materials.
What are the two main categories of mixtures?
Name ONE change of state by HEATING.
-Melting
-Vaporization
*as long as they name one*
Chemical changes result from ________ _________, when two or more substances combine.
Chemical changes result from CHEMICAL REACTIONS, when two or more substances combine
When an object has the same number of positive and negative charges, it is considered electrically __________.
Electrically NEUTRAL.
What are magnets that use electricity called?
What is this called: a homogenous solid mixture that is usually made of two different metals?
ALLOY.
True or false: after a physical change occurs, new matter is formed.
FALSE! When a physical change occurs, the original matter does not change. Only the STATE of the matter changes.
What chemical change is happening when...…..
a substance gains oxygen, for example, when a metal produces rust.
OXIDATION.
TRUE OR FALSE:
Negative charges flowing along a path create an electric current.
TRUE! Negative charges flowing along a path create an electric current.
TRUE OR FALSE:
An electric current produces an ELECTRICAL FIELD.
FALSE: An electric current produces a MAGNETIC FIELD.
What is this called: a homogeneous mixture of a solid dissolved in another substance?
Name two changes of state by COOLING.
-Solidification
-Reverse Sublimation
*They need to name two*
What chemical reaction is caused by living things such as yeasts and bacteria?
Fermentation
Name TWO materials that are good electrical INSULATORS.
Cotton, plastics, and woods are good electrical insulators. *They need to name TWO*
Insulator means electric current does not flow through them.
The earth’s magnetic field is used to find direction with a __________?
COMPASS. **The magnetic needle always points North!*
Name all four methods to separate mixtures.
For example: When icebergs form in very cold water.
Name two examples of NEW MATERIALS.
-Graphene
-Shrilk
-eco-friendly fabrics such as: Eco-friendly fleece and recycled cotton fibre.
In an __________ _________, electricity flows from an energy source (battery), to the device (lightbulb), through a wire or cable. There is also a switch which opens and closes it.
In an ELECTRIC CIRCUIT
Where are earth’s magnets?
There is a MAGNETIC NORTH POLE and a MAGNETIC SOUTH POLE. They are found near the geographic poles.