Uploaded by Diana K.

Physical & Chemical properties

Properties of Matter
Physical Properties
• Something we can observe without changing the substance’s atoms
or molecules.
• Examples:
• What state of matter is the substance?
• Solid, liquid, or gas?
• How hard or soft is the substance?
• Is it shiny or dull?
Physical Properties
• Some changes in physical properties are reversible
• If I melt an ice cube into water, I can refreeze it
• Changing a state of matter is reversible
• Some changes in physical properties are irreversible
• If I crack an egg, I cannot put it back together
• Shaving a piece of metal off a screw is irreversible
Chemical Properties
• The ability of a substance to undergo a change in chemical
• Will change how the atoms or molecules interact
• Chemical Change – Produces matter that looks different from the
original matter
• Burning is a good example
Rust is an Example of Chemical Change
Iron will chemically change when exposed to air
• Two or more elements combined in a particular structure
• They can be broken down into their parts
• Individual elements!
• Example Water! 𝐻2 0
• Made of two hydrogen atoms and one oxygen atom
• Most things in the world are made of compounds
• More than one element
• Dopamine - C8H11NO2
• Theobromine (Chocolate) - C7H8N4O2
• Caffeine - C8H10N4O2
• THC - C21H30O2
• When atom join together, they form molecules
• Molecules can be made of all the same type of element
• In the atmosphere, oxygen atoms pair up - 𝑂2
• Molecules can also be made of different elements
• Example Water! 𝐻2 0
• This is a compound!
Molecules and Bonding
• Two or more atoms are joined by a covalent bond
• Sulfuric Acid = H₂SO₄
Ionic Compounds
• Ions – atoms that have a positive or negative charge
• Postively charged ions are missing an electron
• Negatively charged ions have an extra electron
Ionic Compounds
• Ionic compounds have:
• 1 positive ion
• 1 negative ion
• No electrical charge – Why?
Ionic Bonds
• One atom takes or gives an electron to another
• Ionic bond
• Electron permanently moves to another atom
• Different from covalent bond – they “share” electrons
Ionic Compounds are Crystals
• Positive and negative ions attract each
other like magnets and form a pattern
• Crystals!