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Transcript of CHEMISTRY
Further experiment shows that atom consists of smaller particles called sub-atomic particles.
3 sub-atomic particles are proton, electron and neutron.
Nucleus → where proton and neutrons were
the electron surround the nucleus
in the form of electron cloud. Dalton’s theory PREPARED BY → carries a positive charge of 1.602×10-19C
→ mass 1.673×10-27kg. 2000 times heavy
→ equal in size but opposite in sign to charge
on an electron.
→ mass equal to proton
→ zero electrical
→ negative charge of -1.602×10-19
→ mass 9.11×10-31
→outer part of the atom Sub-Atomic Particles β σ + - e p n attracted to
σ → electron deflection is bigger than
→ shows that electron is lighter than
not deflect → no change Behaviour of Beams of proton, electron and neutron in electric field. We have already learned that ions are atoms that are either missing or have extra electrons. Let's say an atom is missing a neutron or has an extraneutron. That type of atom is called
An atom is still the same element if it is missing an
electron. The same goes for isotopes. They are still
the same element. They are just a little different
from every other atom of the same element. Isotope E-CLOUD NUCLEUS . Proton Neutron Electron σ ISOTOPE + - Proton negative pole Electron positive pole Neutron For example:
There are a lot of carbon (C) atoms in the Universe. The normal ones are Carbon-12. Those atoms have 6 neutrons. There are a few straggler atoms that don't have 6. Those odd ones may have 7 or even 8 neutrons.
As you learn more about chemistry, you will probably hear about carbon-14. Carbon-14 actually has 8 neutrons (2 extra).
C-14 is considered an isotope of the element carbon. If you have looked at a periodic table, you may have noticed that the atomic mass of an element is rarely an even number. That happens because of the isotopes. If you are an atom with an extra electron, it's no big deal. Electrons don't have much of a mass when compared to a neutron or proton.
Atomic masses are calculated by figuring out the amounts of each type of atom and isotope there are in the Universe.
For carbon, there are a lot of C-12, a couple of C-13, and a few C-14 atoms. When you average out all of the masses, you get a number that is a little bit higher than 12 (the weight of a C-12 atom). The average atomic mass for the element is actually 12.011. Since you never really know which carbon atom you are using in calculations, you should use the average mass of an atom. Bromine (Br), at atomic number 35, has a greater variety of isotopes. The atomic mass of bromine (Br) is 79.90. There are two main isotopes at 79 and 81, which average out to the 79.90 amu value. The 79 has 44 neutrons and the 81 has 46 neutrons.
While it won't change the average atomic mass, scientists have made bromine isotopes with masses from 68 to 97. It's all about the number of neutrons. As you move to higher atomic numbers in the periodic table, you will probably find even more isotopes for each element. Z Atoms with the same atomic no. but different mass no.
X A= mass no.
Z = atomic no.
no. of proton in nucleus
no. of electron in neutral atom
also known as proton number
Total no. of proton and neutron
Known as nucleon number Isotopes Atomic no. (Z) Mass no. A A have a charge of and a relative mass of
have a charge of and a relative mass of
have a charge of and a relative mass of THANK YOU JOHN DALTON Protons Neutrons Electrons +1 0 -1 1 AMU 1 AMU 0 AMU ATOMIC STRUCTURE