Atomic Structure & Isotopes Flashcards
John Dalton’s Billiard Ball Model
- First way to represents atom
- Matter is made up of small, indivisible particles called atoms
- Same/diff elements have the same /diff properties
- In chemical reactions, atoms rearrange, nothing new is created of desytyed (conversation of mass)
- Atoms of two or more elements combine in constant ratios to form new substances
J.J. Thomson’s Plum Pudding Model
- Atoms have negatively charged electrons
- Electrons are distributed evenly in an atom
- Positive charges should balance out negative charges to make atom balanced
- States what’s inside a atom
- States everything’s spread out all over the place
Rutherford’s Gold Foil Experiment
High speed particles = positive
Based on JJ model
Gold Foil Predictions
Will have not major deflections due to particles being spaced out evenly
Gold Foil Observations
Used gold foil and shot positively charged particles
The particles are hitting another light charge, being very concentrated, causing deflections
Chadwick’s Neutrons
Nueluces had neutrons (neutral charged particles) and protons (positive charge particles)
Mass of protons= mass of nutrons
Bohr’s Energy Levels
Electrons are in energy levels, holding a specific amount of electrons
Can not be used for bigger elements
The Elements
The atom is the smallest part of an element that has properties of element
Electrons and Protons
of electrons = # of protons in neutral atom
number of electrons = # of protons in neutral atom
Neutrons and Mass
of neutrons Depends on number of mass in nucleus
number of neutrons depends on number of mass in nucleus
Mass number= number of protons + number of neutrons
Isotopes
Different version of an element, with changes of neutrons or mass
Average Atomic mass
- Average of atomic masses of isotopes
- Found on periodic table
- Tells us which isotope is most amount (which number is closer to isotope)
- Decimal value tells us that there are isotopes (must have been added and divided)
- Uses the unit amu (μ)
Determining Isotopic Abundance
- Uses Mass spectrometer
- Figure out percentages/ isotopic abundance
- Turns substances into gas through heating
- Electron beam source enters and interacts with sample
- Vapour is not a charge particle, so it makes gas charged ion
- Ions are accelerators and detectors at end
- Uses computers to determine isotopic abundance
Unstable isotopes
- Some isotopes are unstable and release nuclear radiation
- Nuclear radiation can be energy or small particles
Radioactive decay
When unstable isotopes disintegrate
Nuclear radiation
3 types of nuclear radiation
Alpha particles (α)
Positively charged particles
Have same structure as nucleus in helium atom
Equations use He instead of α
Travels fast
goes through paperonly
Beta particles (β)
Negatively charged particles
Identical to electrons
goes through appe rbut not allimium
Gamma rays (γ)
High form of electromagnetic energy radiation
Radioisotopes
Isotopes that decay to emit nuclear radiation
Uranium
Useful Radioisotopes
- Iodine 131
Treats overactive thyroid gland - Americium 241
Used in smoke detectors - Cobalt 60
Food irradiation - Carbon 14 and potassium 40
Archeology dating
Row
Known as period
Across/horizontal
Same # of energy levels
Column
Known as group
Vertical/down
Same # of valence electrons
electron
outside neucleus
-1 charge
mass close to 0
proton
in neuclus
mass close to 1
+1 charge
neutron
in neuclus
charge of 0
mass of 1
What makes the atoms of one element different from the atoms of another element?
number of protons in neuclues
