Properties of Matter
Hardness definition
How resistant a material is to scratching, deformation, or indentation
What is it called when a solid becomes and gas and vice versa
Sublimation
1
Greek philosopher Empedocles stated that matter consisted of four elements: fire, water, air, earth
6
Heinrich Geissler invented the sealed glass tube that pumped air out and discharged electricity through gases
William Crookes discovered charged particles and that they had mass using this invention
What are the signs of a chemical change?
1. Generates light
2. Heat is produced
3. Precipitate formation
4. Gas is formed (bubbles)
5. Colour change
What is the difference between malleability and ductility?
Malleability - The ability of a substance (usually metal) to change shape
Ductility - The ability of a material to stretch under stress
What is it called when a gas becomes a liquid and vice versa
Gas into liquid: condensation
Liquid into gas: evaporation
2
Democritus developed the first atomic hypothesis, but Aristotle opposed this idea and promoted the 4 element model
7
J.J Thompson experimented on the streams of particles using magnets and electric current and discovered the pieces of atoms we now know as protons and electrons. He proposed the “raisin bun” model of the atom, a positive charged sphere with negatively charged particles embedded in it
4 pure substances and definition
Pure substances cannot be easily divided into smaller subunits
Atoms - single particle
Element - many of the same particle
Molecules - 2+ of the same particle bound together
Compound - 2+ different particles combined
Melting/boiling point definition
Melting point - The temperature that a solid turns into liquid
Boiling point - The temperature that a liquid turns into gas
1. All matter is made of particles
2. Atoms are always in motion and speed up with energy
3. Atoms have spaces between them. More energy = more space
4. Atoms are attracted to each other. High energy = low attraction
3
Alchemists studied matter, experimenting with different chemical substances and devising the system chemical symbols (but still used 4 element system)
8
Henri Becquerel Pierre and Marie Carie experimented with natural radioactivity. Their work and materials they discovered greatly helped with the next proposed model of the atom. They were the first to isolate an element (radium)
What is the structure of an atom, and what are the charges of the subatomic particles?
Protons (positive) and neutrons (neutral) are in the nucleus, and there is an orbital around it with electrons (negative)
Protons define an element (add a proton, different element), electrons define the reactivity, and neutrons are atomic spacers preventing protons from repelling
Solubility definition
The ability of a substance to form a solution with another substance
Explain water freezing using particle theory
The water is made of particles. Energy is being taken from the water, and the particles‘ movement slows down. The loss of energy also causes the spaces between the particles to decrease and the attraction to increase.
4
Robert Boyle, Antoine Lavoisier, Joseph Priestley, and Henry Cavendish found that matter is made out of pure substances (their research disproved the 4 element system)
Ernest Rutherford discovered the second sub-atomic particle of the atom: the proton and the new model of the atom
Ummm so yeah
Oxygen gas
Hydrogen gas
Chlorine gas
Fluorine gas
What are clarity, viscosity, and crystal form?
Clarity - how easily light passes through a substance
Viscosity - the resistance of a liquid
Crystal form - set of crystal faces related by symmetry (???)
Formula for density
For the algebra multiply denominator by itself to cancel it out
5
John Dalton pictured the atom as a tiny, indivisible sphere.
10 & 11
10. Niels Bohr came up with experimental evidence proving that electrons exist in energy levels (shells) orbiting around a positively charged nucleus
11. James Chadwick, using alpha particles, discovered a neutral atomic particle with a mass close to the proton. What he discovered was the neutron (the third sub-atomic particle)
What are the names for the numbers and letters on the periodic table?
The number in the top right is the atomic number (number of protons)
The letter in the middle is the atomic symbol
The number on the bottom is the atomic mass