Chemistry Chapter 4 Flashcards
(52 cards)
Physical properties
Is a characteristic that you can measure or observe without changing the chemical make-up of the matter.
How to observe physical properties
- you can observe with the 5 senses
- you can measure, like using a thermometer to measure temperature.
Physical properties examples
- states of matter
- hardness
- malleability
- ductility
- metaling and boiling points
- crystal form
- solubility
- viscosity
- density
Chemical properties
Describe how a substance behaves during a chemical reaction
How to observe chemical properties
A substance has to change its make-up for us to the chemical properties.
Chemical properties examples
- flammability
- toxicity
- acidity
- heat of combustion
Physical changes
Are those in which the shape,size or state of the matter changes but the substance is will the same.
Chemical changes
You end up with something very different than what you started with. Like mixing chemicals
Chemical changes hints
- new color
- heat or light given off
- bubbles or gas formed
- a solid material forms into a liquid
- difficult to reverse
Matter classification
- pure substance
- mixtures
Pure substances
- Elements: cannot be broken down
- Compounds: 2 atoms together
Mixtures
- Homogeneous (solution): 1 phase (Apple juice or coffee
- Heterogeneous (mechanical mix.): 2 or more phases (pizza or vinaigrette)
Antoine Lavoisier
Was the father of chemistry b/c he recognized that oxygen is an element and is important in playing sorts in different chemical reaction.
Antoine Lavoisier oxygen expirement
When he heated mercury oxide, the chemicals weight decreased was equal to the gas released.
Democritus (Atomic theory)
- proposed that the world is made out of tiny particles that are in constant motion, are different sizes and are separated by empty space.
- no once accept this theory, every one believed in earth, water, air and fire theory (lasted for 2000 years)
John Dalton (Atomic theory)
- billiard ball model
- all atoms are small and invisible
- all atoms of the same element ate the same, different element have different atoms.
Atoms can be rearranged to form new substances in chemicals reactions but the can neither be created or destroyed.
J.J Thompson (Atomic theory)
- the rain bun model
- atoms contain electrons
- the rest of the atom is positively charged cloud with electron evenly distributed throughout
Ernest Rutherford (Atomic theory) gold foil experiment
Rutherford shot positive charges at a gold foil expecting to go through, instead some bounced back
Ernest Rutherford discovered
- the nucleus is a dense positive charge (protons and neutrons)
- the nucleus is surrounded by by a cloud of electrons
- most of the atom is empty space
Neils Bohr (Atomic theory)
- electrons go around the nucleus at fixed points in different orbits.
- 2, 8, 8, 18
James Chadwick (Atomic theory)
- discovered neutrons that are found in nucleus
- they have no charge
- electrons circle through the empty space around the nucleus
What is in an atom?
- Protons ( weight 2000x more than e- )
- Neutrons ( weight 2000x more than e- )
- Electrons ( very light )
Atomic mass
Total number neutrons and protons
Mass number
The total amount of protons and the total amount of neutrons.
