Ch 5 Electrons in Atoms

5.1 Light and Quantized EnergyReview Vocabulary________________ the rays and particles —alpha particles, beta particles, and gamma rays—that are emitted by radioactive materialNew Vocabularyelectromagnetic radiationwavelengthfrequencyamplitudeelectromagnetic spectrum

Main Idea Light, a form of electronic radiation, has characteristics of both a____________ and a _______________

5.1 THE ATOM AND UNANSWERED QUESTIONS Recall that in Rutherford's model, the atom’s mass is concentrated in the nucleus and electrons

move around it. Atom is mostly ____________ space The model does not explain:

o _________the electrons were arranged around the nucleus.o _________negatively charged electrons aren’t pulled into the positively charged nucleus.o the_______________ properties of the elements

a better description of the __________________ was needed In the early 1900s, scientists observed certain elements _____________________________ when

heated in a flame. Analysis of the emitted light revealed that an element’s chemical ________________ is related to

the _______________________ of the __________________in its atoms.

5.1 THE WAVE NATURE OF LIGHT Visible light is a type of _______________________________, a form of energy that exhibits wave-

like behavior as it travels through space. All waves can be described by ____________characteristics.

o The ______________________ (λ) is the shortest distance between equivalent points on a continuous wave.

o The ___________________(ν) is the number of waves that pass a given point per second.o The ___________________ is the wave’s height from the origin to a crest.

The speed of light (__________________) is the product of it’s wavelength and frequency ________. Wavelength and Frequency are __________________related

o As one goes _____ the other goes ____________. Different __________________ of light are different _______________ of light. There is a wide variety of frequencies. The whole range is called a ____________________.

quantumPlanck's constantphotoelectric effectphotonatomic emission spectrum

Sunlight contains a ________________________ of wavelengths and frequencies. A_________________ separates sunlight into a continuous spectrum of colors. The electromagnetic spectrum includes _________ forms of electromagnetic radiation.

Example CalculationCalculate the wavelength of yellow light emitted by a sodium light if the frequency is 5.10 x 1014 Hz.

5.1 the particle nature of light The wave model of light cannot explain all of light’s characteristics. Matter can gain or lose _____________ only in small, specific amounts called _______________. A ____________ is the ________________ amount of energy that can be gained or lost by an atom. Planck’s constant has a value of ________________________--------. _____________________________ proposed in 1905 that light has a _____________________. A beam of light has wavelike and particlelike properties. A ______________ is a ________________of electromagnetic radiation with ______________ that

carries a __________________ of energy. Ephoton = h

Ephoton represents energy. h is Planck's constant. represents frequency.

The ____________________________ is when electrons are emitted from a metal’s surface when light of a certain frequency shines on it.

Long Wavelength

=Low Frequency

=Low ENERGY

Short Wavelength

=High Frequency

=High ENERGY

Atomic Spectra ____________ light is made up of_________ the colors of the ________________spectrum. Passing it through a prism _________________ it. Each________________ gives off its own characteristic colors. Can be used to __________________ the atom. This is how we know what ______________are made of.

5.1 atomic emission spectra

The atomic emission spectrum of an element is the __________________________ of the electromagnetic waves emitted by the atoms of the element.

Each element’s atomic emission spectrum is unique. Light in a neon sign is produced when electricity is passed through a tube filled with neon gas and

excites the neon atoms. The excited atoms ___________________ to _________________________.

Changing the energy Let’s look at a hydrogen atom, with only ______________________, and in the first energy level. ________________________ , or_______________can move the electron up to different energy

levels. The electron is now said to be “_________________” As the electron falls back to the ground state, it gives the energy back as _____________ They may fall down in specific ___________ Each step has a different _____________ The further they fall, more energy is ________________and the higher the_________________. This is a simplified explanation! The orbitals also have different energies inside energy levels All the electrons can move around. Wave-Particle Duality

o J.J. Thomson won the Nobel prize for describing the electron as a particle.o His son, George Thomson won the Nobel prize for describing the wave-like nature of the

electron.

The Math in Chapter 5 There are 2 equations:

c = E = h

________________!

• These are called the _________________________

• Unique to each element, like___________________!

• Very useful for_________________ elements

Examples What is the wavelength of blue light with a frequency of 8.3 x 1015 hz?

What is the frequency of red light with a wavelength of 4.2 x 10 -5 m?

What is the energy of a photon of each of the above?

5.2 Quantum Theory and the AtomReview Vocabularyatom: the smallest particle of an element that retains all the properties of that element, is composed of electrons, protons, and neutronsNew Vocabulary

ground state Main Idea - quantum numberde Broglie equationHeisenberg uncertainty principlequantum mechanical model of the atom

5.2 Bohr’s model of the atom (Planetary Model) Bohr correctly predicted the frequency lines in hydrogen’s atomic emission spectrum. The lowest allowable energy state of an atom is called its _______________________. When an atom gains energy, it is in an _______________________. Bohr suggested that an electron moves around the nucleus only in certain allowed circular orbits.

BUT, Why don’t the electrons fall into the nucleus?o Move like planets around the sun.o In specific concentric circular paths, or orbits, at different levels.o A ____________ (amount) of fixed energy separates one level from another.o Electrons can _______________from one level to another

______________________ of an electrono analogous to the rungs of a ladder

The electron_________________ exist between energy levels, just like you can’t stand between rungs on a ladder

A____________________ of energy is the amount of energy required to move an electron from one energy level to another

Each____________ was given a number, called the ___________________.

atomic orbitalprincipal quantum numberprincipal energy levelenergy sublevel

Hydrogen’s single electron is in the n = 1 orbit in the ground state. When energy is added, the electron moves to the n = 2 orbit. Bohr’s model explained the hydrogen’s spectral lines,

but _____________ to explain any other element’s lines. The behavior of electrons is still not fully understood,

but it is known they do not move around the nucleus in circular orbits.

5.2 The Quantum Mechanical Model _____________ is “quantized” - It comes in chunks. A _________________ is the amount of energy needed to move from one energy level to another. Since the energy of an atom is never “in between” there must be a __________________ in energy. Things that are very small behave _____________________ from things big enough to see. The quantum mechanical model is a_____________________ solution It is not like anything you can see (like plum pudding!) The physics of the ___________________. ____________________ mechanics explains how very small particles behave

o Quantum mechanics is an explanation for _______________ particles and atoms as waves __________________ mechanics describes the motions of bodies much _______________ than

atoms. Louis de Broglie (1892–1987) hypothesized that particles, including electrons, could also have

wavelike behaviors. Has energy levels for electrons. Orbits are not circular. It can only tell us the ____________________ of finding an electron a certain____________ from

the nucleus. The figure illustrates that

electrons orbit the nucleus only in whole-number wavelengths.

The de Broglie equation predicts that all moving particles have wave characteristics. represents wavelengths h is Planck's constant. m represents mass of the particle. represents frequency.

Light is a Particle? Energy is quantized. Light is a form of energy. Therefore, light must be _________________ These smallest pieces of light are called ________________. Photoelectric effect? Albert Einstein Energy & frequency:_____________ related. The energy (E ) of electromagnetic radiation is __________________ proportional to the frequency

() of the radiation.

Heisenberg Uncertainty Principle Heisenberg showed it is impossible to take any measurement of an object without disturbing it. The Heisenberg uncertainty principle states that it is fundamentally __________________ to know

precisely both the _______________ and _______________ of a particle at the same time. The only quantity that can be known is the _________________ for an electron to occupy a certain

region around the nucleus. It is more obvious with the very small objects To measure where a electron is, we use _____________. But the light energy_____________ the electron And hitting the electron changes the_________________

of the light.

Schrödinger – THE QUANTUM MECHANICAL MODEL Schrödinger treated electrons as waves in a model called the _______________________________

of the atom. Schrödinger’s equation applied equally well to elements other than hydrogen. The wave function predicts a three-dimensional region around the nucleus called the ___________

___________________. The atom is found inside a blurry “electron ___________” An area where there is a __________________ of finding an electron.

“One cannot simultaneously determine both the position and momentum

of an electron.”

5.2 atomic orbitals Principal quantum number (n) indicates the relative size and energy of atomic orbitals. n specifies the atom’s major energy levels, called the principal energy levels. ________________ Quantum Number (n) = the _______________level of the electron: 1, 2, 3, etc. Atomic ______________ - regions where there is a high probability of finding an electron. ______________________ - like theater seats arranged in sections: letters s, p, d, and f Energy sublevels are contained within the principal energy levels.

Orbital Shapes s - spherical p - dumbbell d – cloverleaf f - just wild

5.2 atomic orbitals Each energy _________________ relates to orbitals of ________________________.

_________________ number of electrons that can fit in an energy level is:

# of shapes (orbitals)

Maximum electrons

Starts at energy level

s

p

d

f

5.3 Electron ConfigurationReview Vocablularyelectron: a negatively charged, fast-moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom's nucleusNew Vocabulary

electron configurationaufbau principlePauli exclusion principleHund's rulevalence electronselectron-dot structure

Main Idea - A set of __________________ determines the arrangement in an atom.

5.3 ground state electron configuration The arrangement of electrons in the atom is called the ____________________________________. The _________________________ states that each electron occupies the lowest energy orbital

available.

The ________________________________________ states that a maximum of two electrons can occupy a single orbital, but only if the electrons have opposite spins.

__________________________ states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same energy level orbitals.

o When electrons occupy orbitals of _________energy, they don’t __________ up until they have to.

_______________________________ uses noble gas symbols in brackets to shorten inner electron configurations of other elements.

Orbital Diagrams Shows the ___________ associated with a particular electron Shows the _________________ of electrons in an atom Explains bonding and various properties Can be called an ________________________

– Aufbau is German for “building up”

Let’s write the orbital diagram for _______________ We need to account for all ____ electrons in phosphorus The first two electrons go into the ____ orbital Notice the _______________direction of the spins

o only 13 more to go... The next electrons go into the ____ orbital

o only 11 more... The next electrons go into the ____ orbital

o only 5 more... The next electrons go into the ____ orbital

o only 3 more... The last three electrons go into the ____ orbitals.

o They each go into separate shapes (Hund’s)o 3 unpaired electrons

Electron configuration = ______________________

Example Electron configurations

Calcium ___________________ Chromium ____________________

Orbitals fill in an order ______________ energy to higher energy. Adding electrons can change the energy of the orbital. ________orbitals are the most__________. However, ________________ orbitals have a lower energy, and are next best

o Makes them more stable.o Changes the filling order

The electron configurations (for chromium, copper, and several other elements) reflect the increased stability of half-filled and filled sets of s and d orbitals.

____________________________ are defined as electrons in the atom’s outermost orbitals—those associated with the atom’s highest principal energy level.

_____________________________ consists of the element’s symbol representing the nucleus, surrounded by dots representing the element’s valence electrons.