1.c Atomic Structure

Example of weight of 1 mole of atoms

1 mole of an element -> weight is Ar 12 g Carbon 1g Hydrogen 24g Magnesium 32g Sulfur 56g Iron

Mole

6x10^23 = 600, 000,000,000,000,000,000,000 6x10^23, a mole, atoms of hydrogen have a mass of 1 g A mole of carbon have a mass of 12 g moles of atoms = (mass/Ar)

Atoms

Atoms are the building blocks for all substances. The smallest amount of an element that still behaves like that element is an atom. Atoms are made up from even smaller particles: sub-atomic particles.

Group 8

Full outer shell or have 8 electrons in their outer shell. Are unreactive (do not lose/gain electrons easily) Also called Noble Gases Helium (2), neon (2,8), argon (2,8,8,)Krypton (2,8,18,8), Xenon (2,8,18,18,8)

Group 1

Have 1 electron in their outer shell. They are highly reactive metals. Lithium (2,1), sodium (2,8,1), potassium (2,8,8,1)

Group 7

Have 7 electorns in their outer shell HIghly reactive non-metals. Also called halogens. Fluorine (2,7), chlorine (2,8,7), broine (2,8,18,7) and iodine (2,8,18,18,7)

1.11 Isotopes

Isotopes are atoms of the same element with the same number of protons and electrons but different number of neutrons. Isotopes have the same chemical properties but slightly different physical properties. Example Carbon-12, Carbon-13 and Carbon-14. All have 6 protons but they have 6/7/8 neutrons.

Periodic Table cell

Most Periodic tables have 1 numbers against each symbol. CAREFUL. The atomic numbers will always be the smaller number. The other number will be either the mass number of the most common isotope or the relative atomic mass.

1.13 Deduce the electronic configuration of the first 20 Elements from their positions in the Periodic Table.

NEED TO ADD AN IMAGE HERE

1.11 Atomic Number

Number of protons (and electrons) in the nucleus of an atom of an element. Each of the 100 or so elements, have a different number of protons. e.g. if it has 6 protons, it must be carbon.

1.10 Relative Mass and Relative Charge of Proton/Electron/Neutron

Proton Relative Mass = 1 Relative charge= + 1 Electron Relative Mass about 1/2000. Precise number is 1/1836 Relative Charge = -1 Neutron Relative Mass = 1 Relative charge = 0

1.9 Atom structure

Protons and neutrons are in the center of the atom in a cluster called the nucleus. The electrons are found at considerable distances from the nucleus in a series of levels called energy levels or SHELLS. All the mass of the atom is concentrated in the nucleus as electrons weigh hardly anything.

Other sub-Atomic Particles

Quarks, leptons, muons, neutrinos, bosons and gluons. Still, much to learn about them.

3 main Sub-Atomic Particles

The 3 main sub-atomic particles are protons, neutrons and electrons. They are very small and have very little mass and charge.

1.12 How are elements arrange in the Periodic Table

The Periodic Table arrange the elements in order of increasing atomic number. Each of the 100 or so different elements has a different number of protons.

Arrangement of electrons in the atom

The electrons are arranged in shells around the nucleus. The shells don't contain the same number of electrons. Electron shell Maximum number of electrons 1 2 2 -> 8 3 -> 8( initially with up to 18 after element 20) e.g. Aluminium -> 13 -> 2,8,3 Pottassium -> 19 -> 2,8,8,

Avogrado Constant

The number of atoms in the mole, 6x10^23

Atoms are electrically neutral

The positiveness of the protons is balanced by the negativeness of the electrons. Number of electrons = Number of Protons.

1.11 Relative Atomic Mass, Ar

The relative atomic mass of an atom is the average, (mean), mass of an atom on a scale in which the mass of one atom of carbon 12 is 12 units. The relative atomic mass is calculated from the masses and relative abundances of all the isotopes of a particular element. Example: Chlorine has 2 isotopes: Chlorine-35 of 75% abundance and Chlorine-37 of 25% abunance: Ar ((75x35) + (25x37))/100 = 35.5 The relative atomic mass, Ar, of an element in grams contains one mole of atoms.

1.14 Deduce the number of outer electrons in a main group element from its position in the Periodic Table

Vertical columns in the Periodic Table are called groups. Groups contain elements with similar properties. The number given to a group of elements in the Periodic Table is the same as the number of electrons in the outer electron shell of the atoms in the group. E.g. group 1: 1 electron in the outer shell.

Worked Example. What is the mass of 0.1 moles of carbon atoms? (Ar of carbon = 12)

moles = mass / Ar 0.1 = mass/12 mass = 0.1 x 12 mass = 1.2 g

Vocabulary

subatomic electron proton neutron neutrinon Periodic Table Isotope Mole Halogens Avogrado Constant