1. Atomic Structure
Chapter 4 Pg

2. Ancient Greek Models of Atoms
__________-
thought that all substances were built up from only ____ elements: earth, air, fire, and water
matter could be divided an unlimited number of times
believed that all matter consisted of extremely _____ particles that could not be divided
called particles atoms from the Greek
word ________, which means “uncut” or
“indivisible”

3. Dalton’s Atomic Theory
____________- born in England in 1766
Teacher
Interest in predicting the _______, led to his study of the behavior of gases in air
-- Correctly concluded that a gas consists of _________ _________

4. Dalton’s Atomic Theory
Evidence for Atoms
Measured the ______ of elements that combine when compounds form.
Noticed that no matter how _______ or _____the sample, the ratio of the masses of the elements in the compound is always the same (aka fixed composition)

5. Dalton’s Atomic Theory
________ Theory- Dalton proposed the theory that all matter is made up of individual particles called ______, which cannot be divided.
Main Points of Theory
All elements are composed of ______.
All atoms of the same element have the same mass, and atoms of ________ elements have different masses.

6. Dalton’s Atomic Theory
Main Points of Theory continued…
__________ contain atoms of more than one element.
In a particular compound, atoms of different elements always combine in the _____ _____
Not all of Dalton’s ideas about atoms were completely ______, but scientists did not discard his theory, they revised it to take into account new discoveries

7. Dalton’s Atomic Theory

8. Thomson’s Model of the Atom
When rubbed, some materials gain the ability to ______ or _____other
materials.
Based on their ________, they
are said to have either
positive or negative electric
charges.
Objects with ___ charges repel
or push apart.

9. Thomson’s Model of the Atom
Objects with ________ charges attract, or pull together.
Some charged particles can flow from one location to another. A flow of charged particles is called an ________ _______

10. Thomson’s Model of the Atom
J.J Thomson used _______ current to learn more about atoms

11. Thomson’s Model of the Atom
Thomson’s Experiment (pg. 102)
__________ that the beam was a stream of charged particles that interacted with the air in the tube and cause the air to glow.
Placed charged _____ plates at either end-> caused beam to deflect or bend
Observed beam: ________ by negatively charged plate and attracted by positively charged plate

12. Thomson’s Model of the Atom
Evidence for Subatomic Particles
Concluded that the particles in the beam had a _________ charge because they were attracted to the positive plate.
Thomson’s experiments provided the _____ evidence that atoms are made of even ______ particles.
Revised Dalton’s model to account for the ________ particles

13. Thomson’s Model of the Atom
Atom is ______: meaning it has neither a negative nor a positive charge
Negative charges were evenly ________ throughout an atom filled with a positively charged mass of matter
“______ _______” model (may want to think of chocolate chip ice cream)

14. Thomson’s Plum Pudding Model

15. Rutherford’s Atomic Theory
_____, Rutherford discovered that uranium emits fast-moving particles that have a positive charge called _____ ________

16. Rutherford’s Atomic Theory
Hypothesis: (asked student- _______, to find out what happens to alpha particles when they pass through a thin sheet of gold) Predicted that most particles would travel in a _______ path from their source to a screen that lit up when struck.

17. Rutherford’s Atomic Theory
The _______ ______ Experiment
Aimed narrow beam of alpha particles at gold, the material around the ______ produced a flash of light when struck by fast-moving alpha particles
Could figure out ____ of alpha particles by observing the flash after they had passed through the gold
Did _____ support Rutherford’s prediction

18. Rutherford’s Atomic Theory
Gold Foil Experiment continued…
More particles were deflected than he expected
About 1 out of every ______ was deflected by more than 90 degrees
Some alpha particles behaved as though they had struck an object and bounced _______ back

19. Gold Foil Experiment

20. Rutherford’s Atomic Theory
Discovery of the Nucleus
Alpha particles whose paths were ________ must have come close to another charged object
The closer they came, the greater the deflection
_________: the positive charge of an atom is not evenly spread throughout the atom, it is concentrated in a very small central area- ______
Nucleus: a dense, positively charged mass located in the center of the atom

21. Rutherford’s Atomic Theory
According to Rutherford’s model, all of an atom’s _______ charge is concentrated in its nucleus

22. The Structure of an ATOM
Chapter 4 Section 2 Pg

23. Properties of Subatomic Particles
Protons, electrons, and neutrons are _________ particles
Protons:
A __________charged subatomic particle that is found in the nucleus of an atom
Positive charge (amount varies among elements), each proton is _____
Each _________ must contain at least one particle with a positive charge

24. Properties of Subatomic Particles
Electrons
Comes from Greek word meaning “______”
A _________ charged subatomic particle that is found in the space outside the nucleus
Each electron has a charge ____

25. Properties of Subatomic Particles
Neutrons
1932, English physicist J. _________ designed an experiment to show that neutrons exist; concluded particles were ________ because a charged object did not deflect their path
A neutral subatomic particle that is found in the nucleus of an atom
______ is almost exactly equal to that of a proton

26. Comparing Subatomic Particles
Protons, electrons, and neutrons can be distinguished by _____, charge, and location in an atom.
Protons and neutrons have almost the _____ mass
It would take about 2,000 electrons to equal the mass of one proton
Protons and neutrons are _______ nucleus, electrons are in outside space

27. Atomic Number and Mass Number
______ predicted that the atoms of any element are different from the atoms of all other elements
Atomic Number
atoms of any given element always have the same number of protons
Atomic number of an _______ equals the number of protons in an atom of that element
_______ of different elements have different numbers of protons

28. Atomic Number and Mass Number
the mass number of an atom is the ____ of the protons and neutrons in the nucleus of that atom.
Ex: an atom of Al with 13 protons and 14 neutrons has a mass number of 27
Atomic mass is the same
as mass number

29. Isotopes
Every atom of a given element _____ _____have the same number of neutrons.
Isotopes are atoms of the same element that have different numbers of neutrons and different mass numbers
Isotopes of an element have the ____ atomic number but different mass numbers because they have different number of neutrons

30. Modern Atomic Theory
Chapter 4 Section 3 Pg

31. Bohr’s Model of the Atom
Bohr was a ______ physicist who worked with Rutherford
Bohr _______ with Rutherford’s model, but Bohr’s model focused on the electrons
Energy Levels
In Bohr’s model, _________ move with constant speed in fixed orbits around the nucleus (like planets around a sun)

32. Bohr’s Model of the Atom
Energy Levels
Each ________ in an atom has a specific amount of energy
If an atom _____ or ______energy, the energy of an electron can change
The possible energies that electrons in an atom can have are called ______ _______
An electron cannot exist between energy levels

33. Bohr’s Model of the Atom
Energy Levels
An electron in an atom can _____ from one energy level to another when the atom gains or loses energy
The _____ of the jump between energy levels determines the amount of energy gained or lost
Evidence for Energy Levels
Scientists can measure the energy _______ or released when an electron absorbs or releases energy and moves to higher or lower energy levels

34. Bohr’s Model of the Atom

35. Electron Cloud Model
An electron cloud is a ______ model of the most likely locations for electrons in an atom
The cloud is _______ at those locations where the probability of finding an electron is high
Scientists use the electron
cloud model to describe the
possible _______ of electrons
around the nucleus

36. Atomic Orbitals
The ______ _____ represents all the orbitals in an atom
An orbital is a region of space around the nucleus where an ______ is likely to be found
An electron cloud is a good approximation of how electrons behave in their orbitals

37. Atomic Orbitals
Level which an electron has the ____ energy– the lowest energy level– has only one orbital
Higher energy levels have _____ than one orbital
Each orbital can contain _____ electrons at most

38. Atomic Orbitals

39. Electron Configurations
An electron configuration is the __________ of electrons in the orbitals of an atom
The most ______ electron configuration is the one in which the electrons are in orbitals with the _______ possible energies
When all the electrons in an atom have the _______ possible energies, the atom is said to be in its ground state

40. Electron Configurations
If a lithium atom ______ enough energy, one of its electrons can move to an orbital with a higher energy, this ____________ is referred to as an excited state
An excited state is _____ stable than the ground state
Eventually the electron _____ _______and the atom returns to the ground state

41. Electron Configuration
Helium, neon, argon, krypton, and xenon atoms _________ from excited states to the ______ state emit the light you see in “neon” lights