G Chem Ch 4

What are nucleons?

Protons and neutrons in nucleus

What are charges of protons, neutrons, electrons?

Protons +

Neutrons 0

Electrons -

How many protons does an atom have?

Its atomic number

What is the mass number of an atom?

Number of protons and neutrons in an atom

What differentiates isotopes?

How many neutrons are present in the atom

What is the atomic weight of an atom?

Weighted average of masses of all naturally occurring isotopes

What is an anion? Cation?

Anion: negatively charged atom

Cation: positively charged atom

What holds the protons and neutrons in the nucleus together?

Nuclear force

What does it mean to be radioactive?

The nucleus is unstable, so it chages the number of protons/neutrons it has via radioactive decay

What is the parent nucleus? Daughter nucleus?

Parent: nucleus that undergoes radioactive decay

Daughter: more stable nucleus after radioactive decay has occurred

What is alpha decay?

When a large nucleus wants to be more stable, it emits 2 protons and 2 neutrons

The lost particles are large, lose energy quickly, and do not travel far

Skin stops them

What are three types of beta decay?

Beta +, beta -, and electron capture

Beta particles are smaller than alpha, have more energy, and travel further

Aluminum foil, 1 cm glass, and 1 cm plastic stop them

What is beta - decay?

Neutron → proton

Atomic number of the daughter is one greater than the parent, but the mass number is the same

Assume “beta decay" is this unless other info given

What is beta + decay?

Positron emission

Proton → neutron

Atomic number of daughter is one less than parent nucleus, but mass numbers are the same

What is electron capture?

Unstable nucleus takes an electron from its closes electron shell and uses it in the conversion of a proton into a neutron

Atomic number of daughter is one less than parent; mass numbers are the same

What is gamma decay?

A nucleus in an excited state (usually it is after undergoing alpha or any beta decay) emits energy in the form of photons of electromagnetic radiation

Penetrate matter most effectively because the photons do not have mass or charge

Neither atomic number nor mass number changes

What is a half life?

Time it takes for one-half of a sample of radioactive substance to decay

What is the equation of exponential decay curve

See image

What is nuclear binding energy?

Energy released when neutrons and protons were bound to form a nucleus

Equal to energy required to break the nucleus

What is the mass defect?

When nucleons bind, some mass is converted to energy, so mass of nucleus is less than nucleons

change in m = (total mass of separate nucleons) - (mass of nucleus)

Always positive

What is the equation for nuclear binding energy E?

E = (change in m)c²

c = 3 × 10^8 m/s

What is an emission spectrum?

When light is passed through gas, then a prism, the colors that show up (component wavelengths)

Different for each element

What is the energy emited by photons?

E photon = h (c/wavelegth)

c/wavelength = frequency

c = 3 × 10^8 m/s

h = 6.6 × 10^-34 J*s (Planck’s constant)

What is a ground state?

Lowest energy level of an electron

What is an excited state?

Electron absorbs a photon and jumps to a higher energy level

What is the Bohr equation?

En = (-2.178 × 10^-18 J)/n²

n = energy level of the electron

What is an orbital?

3d region around the nucleus where an electron is likely to be found

What is the shape and number of an s subshell orbital?

Every s subshell has one spherically symmetical subshell

What is the number and shape of p orbitals?

Each p subshell has three dumbell shaped orbitals

One on X axis, one on Y, one on z

What are the three rules of electron configurations?

1. Electrons occupy the lowest energy orbital available (Aufbau's principle)

2. Electrons in the same subshell occupy available orbitals singly before pairing up (Hund's rule)

3. There can be no more than two electrons per orbital (Pauli's exclusion principle)

How do electron shells progress as you go down the periodic table and left to right?

1s², 2s², 2p^6, 3s², 3p^6

Increase

What is a diamagnetic atom?

One that has all electrons spin-paired

Must have even number of electrons and all subshells filled

Have no net magnetic field; will be repelled by all externally produced magnetic fields

What is a paramagnetic atom?

Atoms with electrons that are not all spin paired

Produce magnetic fields and are attracted to externally produced ones

How do you know how many orbitals something has and which ones?

Look at what block it is in, look how many rows down

How do you tell which orbitals an atom has?

Look at what block it is in (s, p, d, or f)

Look at how many rows down it is

What does it mean to be isoelectric?

If an ion gains or loses an electron and its configuration matches the configuration of another they are isoelectric

Ex: F- has 1s², 2s², 2p^6 and Neon does too

How do transition metals lose/gain electrons?

They have both ns and (n-1)d orbitals

They will lose valence electrons first, so they lose s electrons before d

What is group 1? Valence configuration?

Alkali metals

ns^1

What is group 2? Valence configuration?

Alkaline earth metals

ns²

What is group VII? Valence configuration?

Halogens

ns²np^5

What is group VIII? Valence configuration?

Noble gases

ns²np^6

What is the d-block?

Transition metals

What are the s and p blocks?

Representative elements

What is the f block?

Rare earth metals

What is the nuclear shielding effect?

Each filled shell between nucleus and valence electrons shields the valence electrons from the full effect of positive protons in the nucleus

What is first ionization energy?

Energy needed to remove the least tightly bound electron

Increases from left to right on table

What is the second ionization energy?

Energy to remove the least tightly bound electron from the cation

Always bigger than the first ionization energy

What is electron affinity?

Energy associated with the addition of an electron to an atom

Positive if energy is released when an electron is bound, negative if energy is gained

How does electronegativity change throughout the table?

Increases from left to right

Decreases as you go down

What is acidity?

Measure of how well a compound donates protons or accepts electrons

Increases from left to right, increases down each family (in relation to size)

What are the periodic trends for atomic radius, ionization energy, electron affinity, electronegativity, and acidity?

Atomic radius: decrease left to right and up

Ionization energy: increase left to right and up

Electron affinity: more negative as you go left to right and up

Electronegativity: increases as you go left to right and up

Acidity: increases left to right and down

How does charge change atomic radius?

Negative ion larger than neutral, which is larger than positive ion

How is energy related to frequency and wavelength?

Directly proportional to frequency

Inversely proportional to wavelength

What are the waves of the electromagnetic spectrum from lowest to highest frequency?

Radio → mu → IR → ROYGBV → UV → X → gamma

What are the waves of the electromagnetic spectrum from lowest to highest wavelength?

Gamma → X → UV → VIBGYOR → IR → mu → radio

What is an absorption spectrum?

Emits all colors except those that are absorbed (where electron transitions occur)

What is an emission spectrum?

All dark with bright bands where energy levels are (where electron transitions occur)

How do transition metals lose electrons?

They first lose them from the highest subshell

Either lose from s or p before d

What is a period?

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