Atomic Structure
This is what all atoms are made of
Protons, neutrons and electrons
How many electrons are needed to complete the first and second energy levels of an atom?
2 for the frist and 8 for the second
These are the three states of matter.
Solid,liquid, gas
How do you know a physical change occurred?
The object changed shape, size and its molecules stayed the same.
Water changing into a gas is an example of what?
Evaporation
This number tells you how many protons are in an atom.
The atomic Number
How do two atoms bond? What do they share?
By sharing their valence electrons.
This is another name for temperature.
Average Kinetic Energy
How do you know a chemical reaction occurred?
color change, gives off light, smell, bubbling/fizzing, change in molecules, absorbs heat or gives off heat, change in texture.
T or F particles in a solid do not move.
FALSE! They vibrate in fixed positions!
These particles are found circling the nucleus of an atom and hold a negative charge.
Electrons
An atom is considered stable when...
It has a full outer energy level
What are the necessary conditions to cause a phase change?
You have to add or remove thermal energy
A glow stick is an example of a ____________ change/reaction, because ________________.
A glow stick is an example of a chemical reaction, because it lights up, changes color, gives off heat, and the molecules change.
Throwing Mentos into soda and seeing the soda bubble/fizz and increase in pressure is an example of a chemical reaction or physical change?
Chemical reaction
This is what we call electrons that are in the outer most energy level
Valence electrons
How many atoms is the molecule oxygen (H20) made up of? How many of each element make up this molecule?
3 atoms
2 Hydrogen
1 Oxygen
When the Average Kinetic Energy increases how does the pressure in a closed container react?
The pressure increases because the particles are moving around quickly and spreading farther away from each other.
How can you prevent a chemical reaction from occurring?
You take away one of the reactants.
An empty glass has a temperature of 100F. When you add ice, the temperature goes down to 0F and stays there for the remainder of the period. This is an example of what?
Physical change. Doesn't change temp. changes state.
An atom has a neutral charge when...
When the number of protons equal the number of electrons.
Why is a hydrogen molecule, H2, more stable than a Hydrogen atom?
By bonding, both atoms now have complete outer energy levels. They now have 2 electrons in their first energy level.
This is why a dented ping pong ball returns to regular shape once placed into a container of hot water.
The water is adding thermal energy (heat) to the air particles inside of the ping pong ball. This causes the kinetic energy (movement) of the air particles to increase, which also increases the pressure on the inside of the ball causing the ball to return to its regular shape.
Why is it difficult to reverse a chemical reaction?
You would have to re-break the bonds and re-form them, and this takes a lot of energy to do.
How are thermal energy, kinetic energy, average kinetic energy and pressure all related?
When you add thermal energy, kinetic energy increases, which increased the Average kinetic energy. An increase in average kinetic energy causes and increase in pressure.