Atomic Structure Notes: Parts of the atom:

Size: px

Start display at page:

Download "Atomic Structure Notes: Parts of the atom:"

Susan Logan
5 years ago
Views:

1 Day 1 Atomic Structure Notes: Parts of the atom: Protons: Positively charged particles found in the Neutrons: Neutral charged particle found in the Electrons: Negatively charged particle found in the. Their mass is so small it is negligible. 0 amu Determining Protons, Neutrons, and Electrons from Periodic Table 6 C Carbon Atomic Number= Chemical Symbol and Atomic mass= the average of the abundance of all of this atom Mass Number= the to the nearest whole number Mass Number=the number of neutrons + Atoms are neutral so in a neutral atom the Protons= Electrons Do some examples of calculated the p, n, and electrons 1. Mg: p= n= e= 2. N: p= n= e= 3. F: p= n= e= Ions: Charged atoms Ions are formed when an atom No other particle is lost or gained in an atom except When determining if you have an ion look in the top right corner of problem and ask yourself Do we have a charge if the answer is no then the. If the answer is yes, then you must look at the charge to figure out the number of electrons. If you have a charge you, if you have a charge you electrons. Examples: 1. F - p= n= e= 2. Mg +2 p= n= e= Isotopes: Atoms of the same element with different C-12 C-13 C-14

2 P=6 P=6 P=6 N=6 N=7 N=8 E=6 E=6 E=6 (Use this to show how you can have the same but have different numbers of neutrons, each of these are isotopes of each other, same element different numbers of neutrons only!) Some isotopes are and we use them to date fossils, like. In the notation of C-14 the 14=the mass number and you must look up the atomic number to find protons, subtract mass number-protons to get neutrons, and the electrons equal the protons. Day 2 Average atomic mass The weighted of each isotope of an atom Example Calculate chromium s average atomic mass using the provided information. Isotope Percent Abundance Mass (amu) Cr % Cr % Cr % Cr To solve a problem you just take the mass number x %(changed to a decimal) for each one then add them together.

The Atom Energy Level # of Electrons Suborbitals 1 2 S 2 8 S,p 3 18 S,p,d (8 involved in bonding) 4-7 32 (8

arrangements Levels s 2 1 1-7 P 6 3 2-7 d 10 5 3-7 f 14 7 4-7 *Each arrangement holds 2 electrons.

3 The Atom Energy Level # of Electrons Suborbitals 1 2 S 2 8 S,p 3 18 S,p,d (8 involved in bonding) (8 involved in bonding) S,p,d,f Arrangement of Electrons Orientation Shape # of # of Energy electrons arrangements Levels s P d f *Each arrangement holds 2 electrons. * Energy levels represent different amounts of energy. * Electrons fill the energy level or sublevel with the least amount of energy.

4 Periodic Table Periodic Table- method of displaying the Organization Groups/Families- of the PT; have similar Periods- of the periodic table Major Sections of the Periodic Table Metals- atoms that electrons to form ions. - of the metalloids -Largest portion of the periodic table. Nonmetals- atoms that electrons to form ions. - of the metalloids Metalloids- a blend between metals and nonmetals -Displays of metals and nonmetals - Referred to as the. Day 3 Periodic Trends Atomic Radius- How big the atom is - Period- decreases as you go from left to right - Group- increases as you go down a group Ionization Energy- energy needed to remove an electron from an atom - Period- increases as you go from left to right - Group-decreases as you move down the periodic table.

5 Electronegativity tendency for an atom to attract an electron to itself - Period- increases as you go from left to right - Group- decreases as you move down the periodic table Ionic Radius- Gain or lose an electron to become an ion - Lose electrons-smaller because the atom has either lost an energy level or there is less repulsion since there are fewer electrons - Gain electrons-larger because the atom has either gained an energy level or there is more repulsion since there are more electrons. Day 4 Electron Dot Valence Electrons- number of electrons in the outer energy level involved in bonding. Group # of VE (except He = 2) Electron Dot- Represents the electrons that are available for bonding. Steps: 1. Find the number of valence electrons 2. Write the symbol for the atom 3. Place one electron on each side before doubling up. Practice: Be,I,Xe,Ge Electron Configuration Electron Configuration- represents the placement of electrons in sublevels.

Steps: Practice: Be,I,Xe,Ge 1. How many electrons? (look for a charge) 2. Starting with the 1 st energy level fill in electrons in order using the periodic table.

6 Steps: Practice: Be,I,Xe,Ge 1. How many electrons? (look for a charge) 2. Starting with the 1 st energy level fill in electrons in order using the periodic table. Day 5 Waves Wavelength, Frequency and Energy of a Photon Wavelength: Frequency: Amplitude: The the wavelength, the the frequency The the wavelength the the frequency The higher the frequency, the higher the energy Electromagnetic spectrum (found on the back of your reference packet): Encompasses all electromagnetic

7 Electromagnetic radiation behaves as a particle and as a wave of energy Photon: Quantum: *When electrons gain energy they jump to a energy level (unstable) *They would rather go back to their ground state or original state so they will energy as soon as they can *When they jump to the ground state from the excited state they or energy. * The energy released is called a amount. This energy is calculated as the energy of a photon. Day 6 Nuclear Notation for writing subatomic particles Superscript = mass # Subscript = charge of particle 1 1 p proton 1 0 n neutron 0-1 e electron 0 1 e positron Stability of an Atom *All elements after Bismuth (atomic #83) are unstable *Unstable atoms have the wrong ratio of protons and neutrons *Unstable atoms become stable by changing their nucleus: this is called DECAY Band of Stability: v For low atomic masses the ratio is 1:1 neutrons to protons v For heavier masses the ratio is 1.5: 1 neutrons to protons

8 The Neutron to proton ratio determines the type of decay process that will occur. You need to know 3 types of Decay 1. Alpha decay Situation: nucleus too heavy Solution: make nucleus smaller by expelling 2 protons and 2 neutrons Example: 2 protons and 2 neutrons is equal to 1 Helium (He) atom decay U α 90Th He He is an alpha particle Beta decay Situation: too many neutrons, not enough protons Solution: Get rid of an electron (Beta Particle) Example: 40 decay K β 20Ca e 3. Gamma Decay Situation: Too much energy Solution: Release energy in form of a gamma ray *means it is excited Example: Pb * Pb + δ decay δ uranium-235 emits an alpha thorium-231 emits a beta and a gamma

protactinium-231 emits an alpha and a gamma actinium-227 emits a beta Day 7 Fission and Fusion Fusion: v Energy released by the sun occurs by a fusion reaction.

Fission: v Our nuclear power plants release energy for power by nuclear fission reactions.

9 protactinium-231 emits an alpha and a gamma actinium-227 emits a beta Day 7 Fission and Fusion Fusion: v Energy released by the sun occurs by a fusion reaction. v If we could produce energy by nuclear fusion we would not have nuclear waste. v These reactions occur at such high temperatures that this is not possible at this time. Fission: v Our nuclear power plants release energy for power by nuclear fission reactions. Day 8 Half-Life is the conversion of an atom of one element to an atom of another element v Either by radioactive decay v Particles bombard the nucleus of an atom 1. If we start with 400 atoms of a radioactive substance, how many would remain after one halflife? 2 half-lives? 3 half-lives? 4 half-lives?

10 2.. If we start with 48 atoms of a radioactive substance, how many would remain after one life? 2 half-lives? 3 half-lives? 4 half-lives? 3. If a sample originally had 120 atoms of C- 14, how many atoms will remain after 16,110 years? 4. If a sample known to be about 10,740 years old has 400 carbon-14 atoms, how many atoms were in the sample when the organism died? Radioactive Substance Radon-222 Iodine-131 Radium-226 Carbon-14 Approximate half-life 4 days 8 days 1600 years 5730 years 1. If we start with 8000 atoms of radium-226, how much would remain after 3,200 years? Plutonium ,120 years Uranium-238 4,470,000,000 2.We start with 20 atoms of plutonium-239, how old would the object be if 5g remained? 3. What was the initial amount of uranium-238, if 15g remain after 8,940,000,000 years?

Atoms and Nuclear Chemistry. Atoms Isotopes Calculating Average Atomic Mass Radioactivity

Atoms and Nuclear Chemistry. Atoms Isotopes Calculating Average Atomic Mass Radioactivity Atoms and Nuclear Chemistry Atoms Isotopes Calculating Average Atomic Mass Radioactivity Atoms An atom is the smallest particle of an element that has all of the properties of that element. Composition