Science 9 - Chapter 1 Test Flashcards
Physical properties of matter
Characteristics of matter that can be observed or measured. Characters that can be observed are called qualitative properties. Character that can be measured are called quantitative properties
Set of properties
The set of properties that a particular substance has is unique. No other substance has that same set of properties. Thus, unknown sentences can be identified by the set of properties they have.
Qualitative
colour lustre - shiny vs matte state - particular temperature ductile - can be pulled into wire malleable - change shape (hammered)
Quantitative
density melting/freezing point boiling/condensation point viscosity - thickness of liquid conductivity- how well it conducts electricity
Compounds and atoms
Compounds are created when atoms of different elements join to form compound atoms. In a compound, all the compound atoms are alike. (We now call Dalton’s compound atoms molecules.)
Atoms cannot be ______
Created or destroyed
Plum pudding model
The “plum pudding” model has the atom as a positively charged sphere, with the electrons evenly distributed on the surface
Dalton’s atomic theory
- all matter is made of atoms which are particles too small to see
- each element has its own kind of atom, atoms of the same element have the same size and mass. Atoms of different elements have different sizes and different masses
- compounds are created when atoms of different elements join to form compound atoms. in a compound, all the compound atoms are alike. (we now call Dalton’s compound atoms molecules)
- Atoms cannot be created or destroyed
What is matter made of?
All matter is made of atoms, which are particles too small to see
Rutherford’s model
Ernest Rutherford’s gold foil experiment led him to propose a nuclear atom, where there was a heavy nucleus in the center, with the electrons occupying the outer areas of the atom.
Atom size
Smallest particle of an element, but are not the smallest particles
Who was a plum pudding model proposed by?
J.J. Thompson proposed the “plum pudding” model
Numbers of particles in atoms
Protons = atomic number
electrons = atomic number (in a neutral atom)
atomic mass = average mass of an element
mass number = protons = neutron*
neutrons = mass number - atomic number
*If you are not told anything else you could make a reasonable guess at a mass number by taking the atomic mass and rounding it to the nearest whole number
Elements and atoms
Each element has its own kind of Atom. Atoms of the same element have the same size and mass. Atoms of different elements have different sizes and masses.
When do chemical changes occur?
When starting materials (reactants) are changed into different materials (products.)
The products will have different properties than the reactants.
Chemical changes occur during chemical reactions.
Difference between chemical change and physical change
Chemical changes change something on a molecular level whereas physical changes rearrange molecules but don’t affect the internal structure
Define the term “Physical Changes”
Physical changes only include changes of state. New materials are not formed. The process is reversible and you can always get back to the original material in the original state.
Give some examples of chemical changes
paper ➡️ ash
raw egg ➡️ cooked egg
potassium ➡️ water ➡️ potassium hydroxide & hydrogen
(One-way arrows show the processes are not reversible)
Give some examples of physical changes
ice ↔️ water
steam ↔️ water
dry ice ↔️ carbon dioxide gas
(Two way symbols show that processes are reversible)
Does irreversibility (not being able to get back to the original reactants) indicate a chemical change?
No, it is not evidence of a chemical change
Define the term “Chemical Changes”
New materials are formed and you cannot go back to the original matter in the original states.
Does a change of state indicate that a chemical reaction has occurred
No
When do chemical reactions occur?
When reactant particles break bonds and rearrange their particles and form new particles.
Evidence chemical reaction
- Heat or light is produced/absorbed
- A colour change occurs
- A new material is formed
- Some original material is used up
- Bubbles appear (new gas forming)
- Cloudiness appears (new solid forming)
Why is the nucleus positively charged?
All the protons are in the nucleus
Electron/Electron Shell
Negative charge {-1}
No mass
Occupies most of the volume of an atom
