Ch. 4 Study Guide Flashcards
What was Aristotle’s thought about all substances?
HINT**There are 2
That they were made up of only four elements: fire, earth, water, air.
There is no limit to the number of times that matter could be divided.
What is the greek word for “atom”?
Atomos
What did Dalton study in his free time? Why?
Gasses; he was interested in predicting the weather
What was Dalton’s evidence for the existence of atoms?
When he measured the masses of elements, he noticed that all the compounds had one thing in common: no matter how large or small the sample, the ratio of the masses are always the same.
What would be a good representation of Dalton’s theory?
Solid spheres
What charges repel and what charges attract?
Like charges repel while opposite charges attract
What did Thompson use to learn more about atoms?
An electric current
Explain Thompson’s experiments.
He used a tube of sealed gas in his experiments. When the current was on in one of the two tubes, the disks became charged and a glowing beam appeared in the tubes. When the current was on in the other tube, the beam bent towards the positively charged plate (there was no charged plates in the first tube).
Describe thompson’s model.
Negative charges were evenly scattered throughout the positively charged atom.
What was Thompson’s model called?
Plum pudding model
Who discovered alpha particles?
Rutherford
What are alpha particles?
Fast-moving particles that have a positive charge
Describe the gold-foil experiment.
Rutherford aimed a narrow beam of alpha particles at gold-foil. The screen around the gold was made up a material that produced a flash of light when struck by a fast moving alpha particle. Five serving the flash, one could figure out the path of the alpha particle after he passed through the gold.
What did Rutherford conclude from the gold for foil experiment?
The positive charge of an Atom is not evenly spread throughout the Atom
According to the weather for model, all of that Adams positive charge is concentrated where?
In the nucleus
What are the three subatomic particle’s?
Protons electrons and neutrons
What kind of charged as a proton have?
A positive charge
Where is the proton found in an atom?
In the nucleus
What kind of charge does an electron have?
A negative charge
Where is an electronic found in an atom?
In the space outside the nucleus
What charge does a neutron have?
A neutral charge
Where are neutrons found In an atom?
In the nucleus
Which two subatomic particle’s have almost exactly equal masses?
Neutrons and protons
What can subatomic particle be distinguished by?
Mass, charge, and location in in atom
What number is always the same in any given element?
The atomic number
What is the atomic number of an atom?
It is the number of protons in and Atom
What is different for every element?
The number of protons, or the atomic number
Which two subatomic particles have the same amount of particles in each atom?
Protons and electrons
What is the mass number of an Atom?
The sum of the protons and neutrons
What is an isotope?
It is atoms of the same element that have different numbers of neutrons a different mass numbers
What did Bohr’s model do that Rutherford’s model didn’t?
Focus on the electrons
How do electrons move in Bohr’s model?
They move with constant speed and fixed orbits around the nucleus
Each electron in an atom has a specific amount of what?
Energy
What is an energy level?
The possible energies that electrons in and atom can have
And electrons energy level is affected by what?
Whether the atom gains or loses energy
An Electron in a high energy level may move up or move down to energy levels?
Down
What evidence is there that electrons can move from one energy to another?
Scientist can measure the energy again when electrons absorb energy and move to a higher energy level. They can also measure the energy released when the election returns to a lower energy level
What was Bohr’s model correct about?
He was correct in assigning energy levels to electrons
What is an electron cloud?
A visual model of the most likely locations for electrons in an atom
What do scientists use the electron cloud model for?
Do you describe the possible locations of electrons around the nucleus
What is an orbital?
A region of space around the nucleus where electron is likely to be found
What is an electron cloud a good approximation of?
How electrons behave in the orbitals
What is electron configuration?
It is the arrangement of electrons in the orbitals of an atom
What is an electron configuration the most stable?
When the orbitals on the lowest possible energy’s
What is ground state?
When all the electrons in an atom have the lowest possible energy
What is the excited state?
It is when electrons move to an orbital with a higher energy level
What assumption did Aristotle make on atoms?
They were based on four elements: earth, fire, water, air
