Transcript Daily Power Point and Warm up
1. Please have these Items on your desk.
October 20, 2015 Day 2
Science Starters Sheet Agenda
Science Starter: •Under the document camera
Table of Contents Update . . . . .
• • Page 51 10/19 Physical/Chemical Changes & Properties
Physical versus Chemical Properties
Reviewing MATTER
• Matter: anything that has mass and takes up space – Mass – the amount of matter in something – Volume – the amount of space something occupies • Which of the following is matter?
– A car?
– A box?
– You?
What is a property?
• Property: a characteristic of a substance that can be observed
Matter can be changed two ways
1.
Physically 1.
2.
Physical reaction Physical change 2.
Chemically 1.
2.
Chemical reaction Chemical change
Physical Property
Physical property: a property that can be observed without changing the identity of the substance .
Examples: • luster • malleability: the ability to be hammered into a thin sheet • ductility: the ability to be stretched into a wire • melting point • boiling point • density • solubility • specific heat
Special Physical Properties
• Melting point: the temperature at which a substance changes from a solid to a liquid at a given pressure • Boiling point : the temperature at which a substance changes from a liquid to a gas at a given pressure water = 100 o C
Physical Changes
• Do
NOT CHANGE THE TYPE OF MATTER
–
Nothing new or different is formed Could be a change in: A. Size B. Change in state C. Color D. Shape
Examples of Physical Changes
A. Boiling B. Freezing C. Dissolving D. Breaking E. Making a
mixture
2 or more types of matter (substances) mixed together • • Not in specific amounts Can be separated physically
Chemical Properties
• Chemical property: a property that can only be observed by changing the identity of the substance Examples: •flammability •ability to rust •reactivity with vinegar
Chemical Changes
• • The composition of the substance changes.
The substances present at the beginning of the change are not present at the end; new substances are formed. The change cannot be “undone.” Picture from www.chem4kids.com
Evidence of Chemical Reactions
• • • • Chemical Reaction: The process by which the atoms of one or more substances are rearranged to form different substances.
Temperature change Color change Gas or solid appears
4. An energy change (Temperature
)
•
Endothermic reaction-
a chemical reaction accompanied by the absorption of heat.
•
Exothermic
reaction a chemical
reaction
that releases energy. The energy “ex”its. It is the opposite of an
endothermic reaction
.
• https://www.youtube.com/watch?v= L-G7pLufXAo
Example of everyday endothermic reactions
• https://www.youtube.com/watch?v=7q04F juT-c
Examples of everyday exothermic reactions
Chemical Changes
• Atoms are re-arranged,
NOT
created or destroyed
Law of Conservation of Matter
• Matter is conserved
type of atoms does not change
– Nothing is created or destroyed
Change of Matter::::Physical change: Identity Retained.
• • •
Change of Matter
This type involves a change in the observable properties of matter without a change of the substance identity. In most physical change of matter, no bonds are broken between atoms and the identity of the subsstance is retained.
Example: Phase Change In a phase change matter changes from solid, liquid or solid but the identity of the substance is retained.
• • •
Change of Matter:::::Chemical change: Identity Changed
This type of change refers to a material changing to a completely different type of material or transformation to a new substance. This process involves bond breaking and bond forming such that material changes identity. Example: Decomposition of water. In the decomposition of water, water molecules H 2 O are broken down to hydrogen and oxygen.
Consider the following examples, which of these are phyiscal and which are chemical change
1.
Heating sugar vs. adding sugar to water 2.
Cutting wood vs. burning wood.
3. The electrolysis of water vs. ice melting.
Answers. . . . . . . ..
•
Physical Change Chemical Change
1. Sugar dissolving Sugar heating 2. Cutting Wood Burning Wood 3. Melting Ice Electrolysis of water