Chem test # 1 - grade 8 Flashcards
All matter is made up of
particles
Particles include:
Molecules, ions, atoms
Atoms:
smallest piece of element - basic/fundamental unit of matter
Molecules:
One or more atoms connected by chemical bonds
Ions:
atom or molecule that has a positive or negative charge
What is random particle motion?
Particles are always in motion
Random particle motion is brownian motion
Brownian motion is caused by the smaller (invisible) particles colliding with the bigger particles, causing them to move randomly.
Do you know what Brownian motion is?
Brownian motion is the random movement of particles suspended in a liquid or gas.
In Brownian motion, lighter/smaller particles move faster than heavier/larger ones. Why?
Smaller/lighter particles move faster than heavier particles because their mass is less. So when they collide with the invisible particles, they move faster because the same amount of force on the smaller particle moves it a lot more than larger particles.
How are particles arranged in gases?
Particles move rapidly
Particles collide with one another + container wall. Take the shape of the container
Particles are very distant from one another
Gas particles have a weak force of attraction
no volume
How are particles arranged in liquids?
Particles are close together
Particles ‘flow’ together and take the shape of their container
They have a medium force of attraction
arrangement: random - no fixed pattern
defnite volume
How are particles arranged in solids?
Particles are very close together
Particles ‘vibrate’ together
They have a high force of attraction
Arrangement - fixed pattern
definite volume and definite shape
Can you explain why gasses exert pressure on the inner walls of containers?
When gasses are confined in a container, their fast moving characteristic and their low force of attraction makes them collide with the walls of the container, therefore exerting pressure
Higher temperature =
Higher kinetic energy
What are the parts of an atom?
Nucleus (protons and neutrons) in the center with electrons orbiting outside it.
Electrons orbit the nucleus in rings called energy levels/shells.
What are the charges and masses of subatomic particles in an atom?
Protons: Positive charge (+1) Mass: 1amu
Neutrons: Neutral charge (0) Mass: 1amu
Electrons: Negative charge (-1) Mass: 1/1800amu
When you count the mass of an atom, you exclude the electrons since they barely make a difference
In the symbol of an element from the periodic table, which number is the proton number? Which is the mass number?
The bigger number and top number is the mass number. The smaller and bottom number is the proton number.
Can you place the electrons of an atom correctly into “shells”?
2 in the first shell, then 8 in the second and third shells. Always add electrons from the inner to outer shells.
You should be able to draw the correct atomic structures for all of the atoms from hydrogen to calcium.
The proton number dictates the number of protons and electrons
The Mass number - the proton number = the amount of neutrons
Neutrons + protons are in the nucleus
The electrons orbit the nucleus in energy levels or shells
The shorthand way to express the electronic structure…
The shorthand way to express the electronic structure gives the number of electrons in each shell. For example: Mg 2, 8, 2. Since there are 2 electrons in the first shell, 8 electrons in the second, and 2 in the third.
What are isotopes?
Isotopes are the same element but with a different amount of neutrons. The chemical properties are the same although sometimes they can be radioactive
Are isotopes radioactive?
Some isotopes are radioactive but not all. An isotope is radioactive because the nucleus decays, emiting rays or particles that can be harmful. The radioactive isotopes are called radioscopes.
The number of protons determines…
what the element is and what chemical properties the element has
Can you explain why Brownian motion occurs?
Brownian motion is caused by smaller, invisible, particles colliding with bigger, visible, particles causing them to move randomly. When there is more force on one side of the particle it will move in that direction.
What is the relationship between pressure and temp?
As the temp increases, the particles move faster and hit the walls of the container with increased force and frequency. This is kinetic energy. Since the particles are exerting more force more frequently on the walls of the container it increases the perssure as well.
What happends when the temperature increases in a gas?
When the temperature increases, the gas particles move faster and there is an increase of kinetic energy due to the particles hitting the walls of the container with increasing force and speed.
What happeneds when the pressure increases in a gas?
When the pressure increases, the gas molecules get closer together and hit the walls of the contaner more often
How can you tell the amount of electrons, neutrons, and protons?
The proton number dictates the amount of electrons
The mass number - the proton number = the amount of neutrons
what is Kinetic particle theory?
The kinetic particle theory states that matter is made up of particles and those particles are consitantly in motion.
What would cause pressure to increase in a gas?
If we decrease the volume of a gas, the molecules get closer tofether and hit the wall of the container more often, therefore increasing pressure
