Unit 1
,History
(Press on 3 dots, and press show outline to quickly access each topic)
Democritus (460 BC - 370 BC)
- Believe there has to be a basic building block of life
- Atomos -> indivisible
- Proposed a theory, atoms are small, hard, indivisible and indestructible particles
John Dalton (1766-1844)
- Brang back Democritus’ theory, based on the premise that atoms of different elements
could be distinguished by differences in their weights. Theory was stated in 1803
- All matter is composed of atoms
- Atoms cannot be made or destroyed
- Different elements have different types of atoms
- Chemical reactions occur when atoms are rearranged
- Compounds are formed from atoms of the constituent elements
- (Atoms of different elements combine in specific proportions to form
compounds) basically what above means
- Assumed simplest compound of 2 elements are binary (wrong)
J.J Thomson (1856-1940)
- Plum pudding model.
- Pudding -> soup of positive charge
- Discovered electron in 1897, proposed 1904
Ernest Rutherford (1871-1937)
- 1909, suggested the following characteristics
- Consists of a small core, or nucleus,
that contains most of the mass
- Nucleus is made up of protons
- Protons are surrounded by electrons
- From the gold foil experiment
- Most positively charged “bullets”
passed through gold foil without
changing course at all
- Some alpha particles did bounce away
from the gold sheet like they hit something solid
- He knew that positive charges repel positive charges
,Niels Bohr (1885-1962)
- Electrons exist in circular orbits (planetary orbits) with electrostatic force from the
nucleus holding them in place
- Electrons can exist in only a series of allowed orbits (energy levels)
- Therefore the energy of electrons is quantized
- While an electron is in one orbit it does not radiate energy
- Electrons can “jump” between energy levels by absorbing and emitting photons
(packets of energy) carrying an amount of energy that equals the difference in the
energy levels of electrons
Erwin Schrodinger (1887-1861)
- Fucking electron cloud bro idk?
James Chadwick (1891-1974)
- Bombarded Be with fast-moving alpha particles, a beam of particles was given off
- The beam was not affected by magnets or charged objects
- must have been made of uncharged particles (neutrons)
, Inside the atom
(absorption isn’t on any quiz/test)
- Atoms are made up of protons, electrons, and neutrons
- Protons and neutrons in the nucleus
- Electrons in orbits
More Bohr
- Bohr found that electrons can exist only in a series of allowed orbits, so the
energy of the electron can only be a specific amount of energy and is stable in the
orbit
- Electrons can jump between energy levels by absorbing or emitting packets of
energy, like photons
- An atom can absorb energy and become excited in one of two ways
- 1. Atom can collide with highly energetic particles in electric current passing
through gas
- 2. Atom can absorb a proton that has an amount of energy equal to the distance
between the energy of the orbit it occupies and energy of a higher orbit
Atomic Light Emission
- Electrons excited to higher energy levels emit light when they fall back down
- When passed through a prism, patterns!!! colours!!
Atomic Math
- Atomic number shows the number of protons (or sometimes electrons if not an ion)
- Atomic mass -> protons + neutrons
Representing elements
- All elements are represented by a symbol (used universally)
Isotopes
- Some atoms of an element may have the same number of protons, they do not have the
same number of neutrons.
,History
(Press on 3 dots, and press show outline to quickly access each topic)
Democritus (460 BC - 370 BC)
- Believe there has to be a basic building block of life
- Atomos -> indivisible
- Proposed a theory, atoms are small, hard, indivisible and indestructible particles
John Dalton (1766-1844)
- Brang back Democritus’ theory, based on the premise that atoms of different elements
could be distinguished by differences in their weights. Theory was stated in 1803
- All matter is composed of atoms
- Atoms cannot be made or destroyed
- Different elements have different types of atoms
- Chemical reactions occur when atoms are rearranged
- Compounds are formed from atoms of the constituent elements
- (Atoms of different elements combine in specific proportions to form
compounds) basically what above means
- Assumed simplest compound of 2 elements are binary (wrong)
J.J Thomson (1856-1940)
- Plum pudding model.
- Pudding -> soup of positive charge
- Discovered electron in 1897, proposed 1904
Ernest Rutherford (1871-1937)
- 1909, suggested the following characteristics
- Consists of a small core, or nucleus,
that contains most of the mass
- Nucleus is made up of protons
- Protons are surrounded by electrons
- From the gold foil experiment
- Most positively charged “bullets”
passed through gold foil without
changing course at all
- Some alpha particles did bounce away
from the gold sheet like they hit something solid
- He knew that positive charges repel positive charges
,Niels Bohr (1885-1962)
- Electrons exist in circular orbits (planetary orbits) with electrostatic force from the
nucleus holding them in place
- Electrons can exist in only a series of allowed orbits (energy levels)
- Therefore the energy of electrons is quantized
- While an electron is in one orbit it does not radiate energy
- Electrons can “jump” between energy levels by absorbing and emitting photons
(packets of energy) carrying an amount of energy that equals the difference in the
energy levels of electrons
Erwin Schrodinger (1887-1861)
- Fucking electron cloud bro idk?
James Chadwick (1891-1974)
- Bombarded Be with fast-moving alpha particles, a beam of particles was given off
- The beam was not affected by magnets or charged objects
- must have been made of uncharged particles (neutrons)
, Inside the atom
(absorption isn’t on any quiz/test)
- Atoms are made up of protons, electrons, and neutrons
- Protons and neutrons in the nucleus
- Electrons in orbits
More Bohr
- Bohr found that electrons can exist only in a series of allowed orbits, so the
energy of the electron can only be a specific amount of energy and is stable in the
orbit
- Electrons can jump between energy levels by absorbing or emitting packets of
energy, like photons
- An atom can absorb energy and become excited in one of two ways
- 1. Atom can collide with highly energetic particles in electric current passing
through gas
- 2. Atom can absorb a proton that has an amount of energy equal to the distance
between the energy of the orbit it occupies and energy of a higher orbit
Atomic Light Emission
- Electrons excited to higher energy levels emit light when they fall back down
- When passed through a prism, patterns!!! colours!!
Atomic Math
- Atomic number shows the number of protons (or sometimes electrons if not an ion)
- Atomic mass -> protons + neutrons
Representing elements
- All elements are represented by a symbol (used universally)
Isotopes
- Some atoms of an element may have the same number of protons, they do not have the
same number of neutrons.
