The Atom + Arrangements of Electrons in the Atom Flashcards
Chemistry
Branch of science that deals with the structure and composition of matter and the reactions needed to change it from 1 substance to another
Matter
Anything that occupies space and has mass
Mixture
2 or more substances MINGLED together but not chemically combined
an Element
a substance that cannot be split into simpler substances by chemical means
Compound
2 or more elements chemically combined
Atoms
smallest particle of an element that can exist on its own
Molecule
2 or more atoms chemically combined together
Ions
charged atoms
Cations
positively charged ions due to loss of electrons from an atom
Anions
negetively charged ions due to gain of electrons by an atom
Prove the particular state of matter
(diagram of ammonia and hydrochloric acid meet to create a ring of ammonium chloride)
Law of Conservation of Matter/Energy/Mass
Matter is neither created nor destroyed during a chemical reaction, it simply changes from 1 form into another
Discharge Tube
- A long glass tube with a metal electrode at each end of the tube
- and the gas inside at very low pressure (almost vaccum)
- passing electricity through tube produced invisible rays,
- moving from the cathode to the anode
- > cathode rays causing glass to fluoresce
Diffusion
spontaneous spreading out of a substance due to the natural movement of its particles
Brownian motion
Random, rapid movement of particles
Name 3 sub-atomic particles (subs.)
Protons
Neutrons
Electrons
Prove cathode rays travel in straight lines
(William Crooke’s diagram of maltese cross casting shadow in discharge tube)
Prove cathode rays posess energy
(William Crooke’s diagram of paddle wheel apparatus)
Dalton’s Atomic Theory
- very small particles called atoms
- atoms are indivisable and indestructable
- all atoms identical to each other in mass and chemical properties
- compounds ->2 or more elements combined together in fixed proportions
Ancient Greek Philosophers proposed that…
-matter composed by ‘indivisable particles’
JJ Thompson found…
-cathode rays attracted to positive charged plate = negetively charged particles
-RATIO of ELECTRON CHARGE to ELECTRON MASS
e/m ratio
-plum pudding model
Electromagnet
a magnet that’s formed by passing a current through a wire wrapped tightly round a piece of metal
Deflection
moved from its original path
In 1891, Johnston Stoney…
named the electron
Robert Milikan…
conducted OIL DROP experiment measuring exact charge on electrons -> substituted the charge into e/m ratio and calculated exact mass of electron
Rutherford Alpha Particle Scattering Experiment
(diagram of alpha particles fired at gold sheet )
[Rutherford Alpha Particle Scattering Experiment]
a VERY LARGE NUMBER of alpha particles…
Therefore…
𝗥𝗘𝗦𝗨𝗟𝗧: passed straight through gold foil -> UNDEFLECTED
𝗖𝗢𝗡𝗖𝗟𝗨𝗦𝗜𝗢𝗡 𝗮𝗯𝗼𝘂𝘁 𝗔𝗧𝗢𝗠𝗜𝗖 𝗜𝗖 𝗦𝗧𝗥𝗨𝗖𝗧𝗨𝗥𝗘: Atoms are mostly EMPTY SPACE
[Rutherford Alpha Particle Scattering Experiment]
MANY alpha particles…
Therefore…
𝗥𝗘𝗦𝗨𝗟𝗧: deflected at small angles and a small number were deflected at larger angles
𝗖𝗢𝗡𝗖𝗟𝗨𝗦𝗜𝗢𝗡 𝗮𝗯𝗼𝘂𝘁 𝗔𝗧𝗢𝗠𝗜𝗖 𝗜𝗖 𝗦𝗧𝗥𝗨𝗖𝗧𝗨𝗥𝗘: Repulsion of particles coming close to small dense concentration of positive charge = NUCLEUS
[Rutherford Alpha Particle Scattering Experiment]
a VERY SMALL NUMBER of alpha particles…
𝗥𝗘𝗦𝗨𝗟𝗧: bounced back along their own path
𝗖𝗢𝗡𝗖𝗟𝗨𝗦𝗜𝗢𝗡 𝗮𝗯𝗼𝘂𝘁 𝗔𝗧𝗢𝗠𝗜𝗖 𝗜𝗖 𝗦𝗧𝗥𝗨𝗖𝗧𝗨𝗥𝗘: alpha particles colliding head on with NUCLEUS
orbit
energy level
fixed path that an electron occupies
Rutherford also…
- Rutherford’s Model of the atom- NUCLEUS + electrons outside
- > Knocked out positively charged particles = PROTONS
- predicted nucleus had other particles wth same mass but NO charge
James Chadwick found…
NEUTRONS and neutrons having same mass as protons
Niels Bohr found…
Orbits and energy levels for electrons
A.M.U.
Atomic Mass Unit
Atomic Number (Z) of an element
no. of protons in the nucleus of an atom of an element
Mass Number (A) of an atom
the sum of the protons and neutrons in the nucleus
Nuclear format of an element
Periodic table elements turned upside down
Isotopes
atoms of the same element with the same Atomic number but different MASS numbers due to different number of neutrons in nucleus of each atom
Reletive Atomic Mass (Aᵣ) of an element
The average mass of an atom of an element reletive to ¹⁄₁₂ the mass of a Carbon-12 atom
Principle of the Mass Spectrometer
positively charged ions are deflected to different extents and seperated on the basis of their reletive masses in a magnetic field
[Mass Spectrometer]
Vapourisation
inlet that contains a heater to vapourise non-gasous samples
[Mass Spectrometer]
Ionisation
electron gun fires electrons at sample atoms, knocking electrons out of sample atoms forming positively charged ions
[Mass Spectrometer]
Acceleration
electric field(negetively charged plates) concentrates ions into narrow beam and causes them to move at high speeds
[Mass Spectrometer]
Seperation
magnetic field seperates ions based on their masses
[Mass Spectrometer]
Detection
ions strike a detection screen and the abuncance of each is recorded
Uses of the Mass Spectrometer:
- To calculate Aᵣ of an element
- to calculate the masses and abundance of isotopes
3 states of matter:
Solids
Liquids
Gases
