Questions about the structure of higher atoms and the mass fraction of atoms

First of all, you have to understand the structure of atoms.

Atoms are made up of the nucleus and electrons outside the nucleus. Whereas, the nucleus consists of neutrons (uncharged) and protons (positively charged). Since atoms are generally not charged, the number of electrons in them = the number of protons.

Since the mass of the electron is very small, when calculating the relative mass of the atom, we generally only calculate the sum of the relative masses of the neutron and the proton. Whereas the relative mass of the proton is , the relative mass of the neutron is . Both can be taken as an approximation of 1.

That is, the relative mass of a proton and a neutron is 1.

The two lines of numbers you are talking about, the one above is the mass fraction, which is the sum of the approximate relative masses of neutrons and protons, and the one below is the number of protons. For example, if a magnesium atom has a proton number of 12, it means that it has 12 electrons and a mass fraction of 24. That is, her neutrons and protons add up to 24.

Then the number of neutrons can also be calculated, which is 24-12=12.

At the top is the mass number, which is the relative atomic mass. Below is the number of protons.

The number of protons is equal to the number of electrons, positive electricity is how many electrons have been run, negative electricity is how many electrons have been gained, and this is how the number of electrons is calculated.

Ion: Trace socks contain 1mol

CaCl2, there are 1molCa2+ and 2molCl+ (+ is the charged) atoms Look at the corner mark: 1molca

2molcl

Look at the whole with a smile: 1mol

CaCl2 is 1mol

CaCl2 molecule.

As for the electrons, depending on the number of charges carried, multiply by the amount of matter in the molecule.

For example, 2molCaCl2 has good potatoes (2+2)*2=8mol

The type of atom is determined by the number of protons in the nucleus The number of protons in the nucleus is different The number of protons and neutrons in the nucleus is different The number of protons and neutrons determines the relative atomic mass of the atom Relative atomic mass The number of protons + the number of neutrons [Wind and rain Tsinghua Road] will answer for you.

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1. The type of atom is determined by the number of protons and neutrons.

2. What does the total number of protons and neutrons (i.e., the mass number) determine? The type of element is determined by the number of protons.

The type of atom is determined by (number of protons, number of neutrons).

The type of nuclide is determined by (number of protons, number of neutrons).

This is critical.

Determines the type of element: the number of protons.

Determines the type of atom: number of protons + number of neutrons.

Determine the number of ion charges: the number of protons vs the number of neutrons.

Determines the chemical properties: the outermost electron.

1 Quantity of Matter = Mass Relative to Molecular Mass.

So the amount of a substance of 11g of CO2 = 11 44 = the number of molecules = the amount of a substance * Avogadro's constant.

So the number of molecules = = pcs.

The amount of carbon atom = , the mass of carbon atom = = 3g, the number of carbon atoms = the amount of oxygen atom matter = = , the mass of oxygen atom = 16* = 8g, the number of oxygen atoms = * 2 = pcs.

2 Quantity of Matter = Mass Relative Molecular Mass.

So the amount of H2SO4 substance = =

The amount of oxygen atom matter = = , the number of oxygen atoms = * = the amount of 3 substances = the number of molecules Avogadro's constant.

So the amount of the substance containing the H2SO4 molecule = ( = A molecule of H2SO4 has two H+ and one SO4 2- so the amount of H+ substance that can be produced when dissolved in water = =

SO42- Amount of substance=

4 Ratio of the number of molecules = Ratio of the amount of matter.

So the ratio of the number of molecules of 18 g of H2O to 16 g of O2 = (18 18):(16 32) = 2:1

Ratio of atomic numbers = (2*3):(1*2) = 3:1

This statement is false, oxygen has isotopes, aerobic 16 and oxygen 18. This is the mass of the oxygen 16 atom, but the oxygen 18 is not. But his calculation method is correct, the molar mass is the mass possessed by 1mol of particles (atoms, molecules, or ions), then the actual mass of an atom m (atom) = molar mass m Avogadro's constant na.

The atomic mass of one oxygen 16 is equal to these.