The atomic mass of an element is the number of times of an atom of that element is heavier than an atom of carbon taken as 12. In simpler way, atomic mass is number of protons present in nucleus of an atom, which is a characteristic of an chemical element and is determines place of the element in the periodic table. Mass number is total number of protons and neutrons. If an uncharged atom looses electron from its outermost shell, it becomes cation, which is positively charged species. Atomic number and mass number do not change if electron goes out of an atom.
Uncharged copper after loosing two electrons is converted to 
which can be represented as follows:
→
Answer:
The order of reactivity of metals is as follows, Potassium > Sodium > Lithium > Calcium > Magnesium > Aluminium > Zinc > Iron > Copper > Silver > Gold.
Explanation:
The reactivity of elements (metals) towards water decreases towards the right in a period. It also increases down the group. But zinc is more reactive towards water than iron. Hence the correct order is:
Iron<Zinc<Magnesium<Sodium
Answer:
See explanation
Explanation:
Electro negativity refers to the ability of an atom in a molecule to attract the shared pair of electrons of a bond closer to itself.
In a molecule, the polarity of bonds is determined by the relative electro negativity of the bonding atoms. If the difference in electro negativity between the atoms in a bond is significant, such a bond is polar in nature e.g H-Cl, H-Br, C-F, etc.
However, the occurrence of polar bonds in a molecule alone does not guarantee the polarity of the molecule. The polarity of a molecule also depends on the shape of the molecule since dipole moment is a vector quantity.
A molecule is polar when the resultant dipole moment which is determined by the shape of the molecule is non zero.
For instance, CO2 contains two polar C-O bonds but the molecule is non polar because the two dipole moments cancel out. Also, symmetrical molecules are nonpolar irrespective of the presence of polar bonds in the molecule.
The coefficients should be 1; 6; 4; 4 and the coefficient of CO2 is 4
It shows the atomic number
