Atoms
Atoms
basic unit of a chemical element
Greek philosopher Democritus proposed that all matter can be decided into smaller pieces until there is a single indivisible particle is reached (~400 BCE)
Aristotle rejected the idea of an atom and state that everything is made up of earth, water, air and fire and they were either dry, wet, cold or hot (~450BCE)
John Dalton proposed that all matter is made up of particles called atoms and all atoms of an element are the same, and atoms of different elements are different
Atoms are also believed to be rearranged to for new substances in chemical reactions but don’t create nor destroy any previous ones (1807)
J.J Thompson discovered that small negatively charged particles could be emitted by very hot materials and are attracted to the positive ends of a circuit.
Positive and negative charges were known to attract each other, therefore he concluded that these particles must be negatively charged and Thomas called them electrons
Thomas’s model was called “plum pudding”
Ernest Rutherford tested Thompson’s model and predicted that of positive and negative charges were distributed throughout atoms, then tiny positively charged particles shot at a thin piece of golden foil would pass through the foil
In Rutherford’s revised model, the center of the atom has a positive charge, the center is called the nucleus, which contains most of the atom’s mass but occupies a very small space
The nucleus is what made some particles bounce back siring the experiment
The suckers is surrounded by a cloud of negatively charged electrons of an atom and has employ space between them
Bohr says that electrons orbit the nucleus and each electron in an orbit has a definite amount of energy
The farther the election from the nucleus, the greater the energy
Electrons can not be between orbits but can jump from orbit to orbit (but do note that there is no specific course that an electron must take and that it is random and different every time, but it can still jump to another electron’s orbit instead)
The number of protons and neutrons are the same and electrons can vary. But the number of rings depends on the amount of electrons it has. The ring number cap goes “2, 8, 8, 18…”. Every element also starts off neutral, but then later gains charges by losing (becomes positive) or gaining (becomes negative) elections. This happens because all of the elements want to be stable. Which means having the desired amount of electrons on its outermost shell (which is the maximum amount).
Reading the periodic table:
The atomic number identified the element, number of protons in the nucleus and number of electrons in a neutral atom
The mass number of an atom in AMU (atomic mass units) and it can be used to find the number of neutrons
Number of neutrons = Mass Number - Atomic Number
Organized by atomic number
Lightest have the lowest numbers
Equations:
Groups:
Alkali metals:
Group 1
Very reactive
Not found naturally as pure elements
Alkaline earth metals:
Group 2
Fairly reactive metals
Not as reactive as group 1
Halogens:
Group 17
Toxic
Reactive
Noble gasses:
Group 18
Completely non-reactive
All gasses
Found in atmosphere as pure elements
Keywords:
Scientific theory — an expression of our best understanding of a phenomenon, based on scientific reasoning and/or evidence
Protons — a positively charged particle that is found in an atom’s nucleus
Neutrons — a neutrally charged particle that is found in an atom’s nucleus
Electrons — a negatively charged particle circling around the atom’s nucleus
Atoms
Atoms
basic unit of a chemical element
Greek philosopher Democritus proposed that all matter can be decided into smaller pieces until there is a single indivisible particle is reached (~400 BCE)
Aristotle rejected the idea of an atom and state that everything is made up of earth, water, air and fire and they were either dry, wet, cold or hot (~450BCE)
John Dalton proposed that all matter is made up of particles called atoms and all atoms of an element are the same, and atoms of different elements are different
Atoms are also believed to be rearranged to for new substances in chemical reactions but don’t create nor destroy any previous ones (1807)
J.J Thompson discovered that small negatively charged particles could be emitted by very hot materials and are attracted to the positive ends of a circuit.
Positive and negative charges were known to attract each other, therefore he concluded that these particles must be negatively charged and Thomas called them electrons
Thomas’s model was called “plum pudding”
Ernest Rutherford tested Thompson’s model and predicted that of positive and negative charges were distributed throughout atoms, then tiny positively charged particles shot at a thin piece of golden foil would pass through the foil
In Rutherford’s revised model, the center of the atom has a positive charge, the center is called the nucleus, which contains most of the atom’s mass but occupies a very small space
The nucleus is what made some particles bounce back siring the experiment
The suckers is surrounded by a cloud of negatively charged electrons of an atom and has employ space between them
Bohr says that electrons orbit the nucleus and each electron in an orbit has a definite amount of energy
The farther the election from the nucleus, the greater the energy
Electrons can not be between orbits but can jump from orbit to orbit (but do note that there is no specific course that an electron must take and that it is random and different every time, but it can still jump to another electron’s orbit instead)
The number of protons and neutrons are the same and electrons can vary. But the number of rings depends on the amount of electrons it has. The ring number cap goes “2, 8, 8, 18…”. Every element also starts off neutral, but then later gains charges by losing (becomes positive) or gaining (becomes negative) elections. This happens because all of the elements want to be stable. Which means having the desired amount of electrons on its outermost shell (which is the maximum amount).
Reading the periodic table:
The atomic number identified the element, number of protons in the nucleus and number of electrons in a neutral atom
The mass number of an atom in AMU (atomic mass units) and it can be used to find the number of neutrons
Number of neutrons = Mass Number - Atomic Number
Organized by atomic number
Lightest have the lowest numbers
Equations:
Groups:
Alkali metals:
Group 1
Very reactive
Not found naturally as pure elements
Alkaline earth metals:
Group 2
Fairly reactive metals
Not as reactive as group 1
Halogens:
Group 17
Toxic
Reactive
Noble gasses:
Group 18
Completely non-reactive
All gasses
Found in atmosphere as pure elements
Keywords:
Scientific theory — an expression of our best understanding of a phenomenon, based on scientific reasoning and/or evidence
Protons — a positively charged particle that is found in an atom’s nucleus
Neutrons — a neutrally charged particle that is found in an atom’s nucleus
Electrons — a negatively charged particle circling around the atom’s nucleus