Answer:
A) All the elements are composed of atoms.
d) Atoms cannot be created or destroyed in any chemical changes.
c) An atom of one element cannot be changed into an atom of a different element.
Explanation:
The main postulates of Dalton atomic theory was:
1) The matter is composed of atoms and atom is indivisible particle which can not be destroyed.
2) The atoms of an element are identical.
3) The atoms of different elements are combining with definite proportion and form compounds.
4) The atoms of different elements are different from each other.
5) During chemical reaction rearrangement of atoms occur and form new compounds.
You're right, it's a solid at room temperature :)
Left side:
Mg= 1
O= 2
H= 4
Cl= 2
Right side:
Mg= 1
O= 2
H= 4
Cl= 2
We generally represent an element by its symbol. provided with the atomic number and mass number or atomic mass
Atomic number is the number of protons present in an element. It is constant for an element.
The mass number of element is the sum of number of protons and number of neutrons
The atomic mass is the total mass of all the protons and neutrons present in the element (in its nucleus).
the number of electrons is equal to number of protons in a neutral atom of element.
The mass of electrons is not included in the total atomic mass of element as it is very low.
So here
12 = it is the number of protons = atomic number of element.
The true statements are
The combined mass of protons and neutrons is 24.305
Answer:
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