Chemistry periodic table help?

Question

can you explain electron configuration CLEARLY. plus i want to know what does the periodic table tell about valence electrons i.e which group has how many valence. also explain equilbrium and specific heat

Answer 1

Ok, that's four questions :P

I'll answer them in a more suitable order (:

1) The periodic table and electrons?

Each element in the periodic table has TWO NUMBERS

- MASS NUMBER (The LARGER number. tells us the total number of PROTONS and NEUTRONS in the atom, and hence, the ATOMIC MASS)

- ATOMIC NUMBER (The SMALLER number.Tells us the number of PROTONS in an atom's nucleus.

In regard to electrons, the ATOMIC NUMBER is most important, for the following reasons:

- The OVERALL CHARGE on an atom is NEUTRAL

- PROTONS = 1+ (single positive) charge,

- ELECTRONS = 1- (single negative) charge

- Therefore; THE NUMBER OF PROTONS AND ELECTRONS IN AN ATOM ARE EQUAL

ATOMIC NUMBER = NUMBER OF ELECTRONS (in an atom.)

The periodic table is arranged in

- ROWS called PERIODS

- COLUMNS called GROUPS

There are 8 groups in the periodic table.

The GROUP NUMBER = NUMBER OF VALENCE ELECTRONS (electrons in the OUTER, or VALENCE shell of an atom)

2) Electron configuration?

Electrons are arranged in SHELLS (accomodating different numbers of electrons) orbiting the NUCLEUS of an atom.

- Shell 1 has TWO ELECTRONS

- Shell 2 has EIGHT ELECTRONS

- Shell 3 has EIGHT ELECTRONS

- Shell 4 has EIGHTEEN ELECTRONS

Within these shells are SUBSHELLS.

Subshells each have a certain amout of ORBITALS

To get your head around it, think of them as different 'levels'

SHELL (highest) ---> SUBSHELL (different kinds) ---> ORBITAL

There are different kinds of subshells, each with different shapes

- S SUBSHELL (has ONE ORBITAL, holds 2 electrons)

- P SUBSHELL (has THREE ORBITALS, holds 6 electrons)

- D SUBSHELL (holds 10 electrons)

The subshells are filled in a CERTAIN ORDER in each shell, according to ENERGY LEVELS OF ELECTRONS

THIS IS CALLED AN ELECTRON CONFIGURATION!!!

The following is THE ORDER OF FILLING (Shells are separated by dashes, -)

1S^2 - 2S^2 2P^6 - 3S^2 3P^6 - 4S2 - 3D10

PLEASE don't look at this and get scared!!! Each number and letter means something different (: [FOR EACH SET OF 3 CHARACTERS, which represents a SUBSHELL]

- The LEFT NUMBER = ENERGY LEVEL OF THE ELECTRON

- The LETTER = SUBSHELL TYPE

- The SUPERSCRIPT NUMBER = NUMBER OF ELECTRONS

(You'll notice that the 4S^2 Subshell fills BEFORE 3D^10. this is because it is at a LOWER ENERGY LEVEL than the 3D^10 subshell. For this reason, 3D^10 is part of the 4TH SHELL)

(This is a very difficult concept to grasp. If you'd like a further explanation, i'd be glad to help (:. My msn is [e-mail])

3) EQUILIBRIUM

A DYNAMIC EQUILIBRIUM is best explained using an example.

H+ + OH- <--> H2O (REVERSIBLE REACTION)

- This is a REVERSIBLE REACTION

- This means that it can proceed in EITHER DIRECTION (so,

H2O ---> OH- + H+ can ALSO happen.)

Now, obviously, one of these reactions occurs at a FASTER RATE THAN THE OTHER

At a certain point, the reactions will begin to occur AT THE SAME RATE

This condition is called DYNAMIC EQUILIBRIUM

- Rate of FORWARD REACTION = Rare of REVERSE REACTION

- In other words, PRODUCTS formed at same rate as REACTANTS

For a dynamic equilibrium to be established:

- A CLOSED SYSTEM IS REQUIRED (I.E. reactants are closed off from surroundings, including outside air.)

WHENEVER A CONDITION AFFECTS THE POSITION OF A DYNAMIC EQUILIBRIUM, THE EQUILIBRIUM WILL SHIFT TO MINIMISE THAT CHANGE

The 'CHANGE' can be

- Temperature

- Concentration

- Pressure (for gasses)

- UV light (for photo-chemical reactions)

If you want further information, just ask me about 'le chatileir's principle (:

4) Specific heat capacity?

The ENERGY required to increase ONE MOLE of a substance's temperature by ONE DEGREE KELVIN (absolute temperature)

It's measured in JOULES per GRAM per DEGREE KELVIN

(J g^-1 K^-1)

I'm guessing you're doing A-levels?

Just finished mine lol :P

Just ask if you need help with anything else.

Answer 2

The periodic chart is columned to have the same number of valence electrons for the elements in the column.

The rows tell the "shells" starting at the top (1) and working down. All rows END with 8 electrons in the outer shell, thus the octet rule. Length of rows indicate how much packing occurs in lower shells.

SpHt and "equilibrium" are not properties commonly found on the chart, although SpHt of the elements is sometimes. Most SpHt data is for compounds of which there are MANY!