Atoms and Atomic Structure

Proton and neutron has a size of 10-13 cm (approx. 1,5-2 fm).

The diameter of the electron may be cca. 10-17 m but this is only a calculated value and is not very sure.

An atom of 18 protons is an atom of Argon, which is a Noble/Inert Gas.

Consequently being an inert gas it does NOT gain extra electrons.

So an atom of Argon does NOT have 22 electrons. It only has 18 electrons, . in order to remain neutrally charged. It does NOT form an ANION .

The number of protons indicates the element(name).

The number of neutrons indicates the isotopic mass.

Graphite is an allotrope of Carbon .

Other allotropes of carbon are Diamond and Buckminster Fullerene.

An allotrope is an element that displays different physical characteristics.

Aluminum has 13 electrons arranged in 3 energy levels. The first two levels are filled, each with 2 and 8 electrons, respectively, and the third level has 3 electrons. Since aluminum has equal numbers of protons and electrons (13 each), the positive charge of the protons is balanced by the negative charge of the electrons, resulting in no overall electrical charge on the aluminum atom.

The overall charge on an atom of aluminium is 'ZERO' . The number of protons equals the number of electrons.

An atom with three extra electrons is NO longer an atom but an ANION.

e.g. N2 + 6e^(-) = 2N^(3-)

A moleculae of nitrogen contains two atoms. Six electrons combine to form two ANIONS (N^(3-))

If there were extra electrons in an atom, it would no longer be an atom , but an ANION.

e,g,

Cl2(g) + 2e^(-) = 2Cl^(-)

A moleculae of chlorine has combined with two electrons (e) to form two chloride anion (Cl^(-)).

The each chlorine atoms has gained an extra electron .

Disregard the electrons, as their relative mass is insignificant to that of protons and neutrons. To find atomic mass, add the numbers of protons and neutrons: 5 + 6 = 11 is the mass number.

The oxidation number of the preceding atom

e.g. KMn(VII)O4.

The oxidation number tells us the number of electrons in the outermost (valence( shell, that are involved in bonding with electrons of other atoms.

So Seven (VII) of manganese's electrons are involved in bonding. However, NOT all electrons in the valence shell are in volved in bonding ; there may be 'lone pairs'.

Generally, oxidation numbers refer to Transition Elements ( between Groups (II) & ( III). However, other non-metallic elements may also exhibit variable oxid'n numbers. e.g. Sulphur or Nitrogen.

Lithium, regardless of its atomic mass, has 3 protons.

The Carbonate anion has four atoms.

1 x carbon

3 x oxygen

Giving the formula ' CO3^(2-)' It does NOT exists in its own right as a substance, but in combination with a metal. e.g. CaCO3 Calcium carbonate.

What is ' MG plus 2'????

If you mean ' Mg^(2+) ' Which is the magnesium cation.

Elemental magnesium has 12 protons and 12 electrons in one atom. giving it the symbol ' Mg '

Magnesium readily ionises, by losing two electrons ' So now a particle of magnesium has 12 protons(+) and 10 electrons(-).

We now do a little sum

(+)12-10 = (+)2

So the magnesium ion has the symbol ' Mg^(2+) '.

NB When n atom loses or gains electrons electrons it is NO longer an atom, but an ION.

NNB Elemental symbols of 2 letters are written as ; first letter is a CAPITAL letter and the second letter is small/lower case . Hence magnesium is ' Mg', NOT 'MG'. There are NO elements with a single letter 'M' nor 'G' as elemental symbols. This is the international standard, and understood world-wide, and is done to avoid confusion. .

NNNB The charge on an ion is written superscript, with a number and then +/- sign as appropriate. Not in descriptive language.

When two or more compounds are mixed together, they do not undergo a chemical reaction to form new substances. Each compound maintains its own chemical identity and properties. This is a physical change rather than a chemical change.

Protons.

The nucleus of an atom is composed of protons and neutrons.

The protons are positively charged (+) particles.

The neutrons are particles that have no charge.

The sum of all the protons and neutrons in a nucleus gives an atom its Atomic Mass.

Outside the nucleus are energy shells of electrons which are negatively(-) charged particles. However, by mass , they are much smaller than protons and neutrons, so do not add to the atomic mass.

Neutrons.

The columns down are named 'GROUPS.

The lines accross are name ' PERIODS.

NB Have a look on the 'web' (WWW') for Chemical Galaxy spectacular display of the Periodic Table in a completely different form .

Each spoke is a Group and each circle/loop is a period.

If chromium followed the expected pattern of electron configuration, it would have a configuration of [ \text{Ar} , 4s^2 3d^4 ]. However, chromium is an exception due to its stability preference, which leads to the half-filled 3d subshell. By having the configuration [ \text{Ar} , 4s^1 3d^5 ], chromium achieves a more stable arrangement.

Electron (-1)

Positron (Positive electron) (+1)

Neutron ( 0 )

Proton ( +1)

NB A positron is a particle of an electrons mass, much less than a proton, but has a positive charge.

To find the number of valence electrons of an element using the periodic table, you can look at the group number of the element. The group number indicates the number of valence electrons. For example, elements in Group 1 have 1 valence electron, elements in Group 2 have 2 valence electrons, and so on.

First, convert the mass of carbon dioxide to grams by dividing by 1000: 220 mg = 0.22 g. Next, use the molar mass of carbon dioxide (44 g/mol) to calculate the number of moles: 0.22 g / 44 g/mol = 0.005 moles of carbon dioxide.

This is called an "octet" of electrons. It could also be called a "closed shell", since it is characteristic of the outer shell of noble gas atoms.

Beryllium.

Its full electron configuration is ' 1s2, 2s2 , '.

All alkali earth metals have 2 valence electrons.

The center of an atom is called the nucleus. It consists of positively charged protons and neutral neutrons, tightly packed together. The nucleus contains most of the atom's mass in a very small volume.

Neon(Ne) is an INERT /NOBLE gas. It does not react with anything.

It exists as monatomic atoms.

Its atomic structure is ; -

Protons. 10

Electrons ; 10

Neutrons ; 10 ( commonest isotope).

Its atomic No, is '10'.

Its Atomic Mass is ; 20. ( 10 protons + 10 neutrons = 20 nucleons).

Argon(Ar) is an INERT /NOBLE gas. It does not react with anything.

It exists as monatomic atoms.

Both gases are found in the Periodic Table, in Group(18)/Noble Gases.

Its atomic structure is ; -

Protons. 18

Electrons ; 18

Neutrons ; 22 ( commonest isotope).

Its atomic No, is '18'.

Its Atomic Mass is ; 39.9. ( 18 protons + 22 neutrons = 40( ~39.9 nucleons).