RT 203-MOD 1

Ancient Greeks

All matter could be described as combinations of these four basic components (air, water, earth, and fire) in various proportions, modified by four basic essences: wet, dry, hot and cold

John Dalton

1808

John Dalton 1808

Theorized that all elements were composed of tiny indivisible and indestructible particles called atoms, and were unique to each element in their size and mass

• composed of fundamental building blocks

• smallest particle that has all the properties of an element

what are atoms?

Indivisble

Atomos (greek word)

John Dalton

Theorized that compounds were formed by molecules, and molecules by fixed ratios of each type of constituent atom, resulting in a predictable mass

Hooks and eye - physical combinations

John Dalton

Dmitri Mendeleev

Advanced Dalton’s work by organizing the known elements into the periodic table, which demonstrates arrangement of elements in order of ascending atomic mass and on the basis of the repetition of similar chemical properties

First periodic table of (65 elements)

Dmitri Mendeleev

Joseph John Thomson

• Discovered electrons (experimented with the cathode ray tube)

• only difference between atoms of one element and the atoms of another was thought to equal was known to be electrically neutral

JJ Thomson

• Plums pudding

• Plums = negative charge

• Pudding = shapeless mass of uniform

1890

JJ. Thomson

1911

Ernest Rutherford

Ernest Rutherford

• tiny virsion of the miniature solar system

• suggested that there were tiny spaces, holes or at the atomic level which proved the atom consists mostly of empty space

1913

Niels Bohr

Niels Bohr

• expanded rutherfords’s work and proposed a model for atom that is considered the most representative of the structure of matter

• it is linked to the miniature solar system

Erwin Schrödinger

• foundation of modern physics and is only known as quantum or wave mechanics

• Orbital electrons (occupying any location within the atom)

Nucleus

it contains protons and neutrons (collectively knows as nucleons)

Quarks, gluons

Both comprises even smaller sub-nuclear structures called

Quarks

These are elementary subatomic particles that serve as the fundamental building blocks of composite matter most notably protons and neutrons

Gluons

It serves as the subatomic "glue" that binds quarks together to form composite particles like protons and neutrons

10^-10m

the radius of an atom is approximately

10^-14m

the radius of the nucleus is about

Electron, Proton, Neutron

Fundamentals of particles

Proton

• one unit of positive electrical charged

• mass: 1.673 × 10^-27kg

• 1.00867 amu

• Atomic mass no. 1

Electron

• very little mass yet moving extremely fast

• one unit of negative electrical charge

• Mass: 9.109×10^-31kg

• 0.000548 amu

• Atomic mass no. 0

Neutron

• no electrical charged

• Mass: 1.675 ×10^-27kg

• 1.00867 amu

• Atomic mass no. 1

anion, negative ion

If the atom gains an extra electron, the negative charges will outnumber the positives and the atom will have a net negative charge

nonionized state

an atom is electrically neutral because the number of protons equals the number of electrons

cation, positive ion

If the atom loses an electron, the positive charges will outnumber the negative charges and the atom will have a net positive charge

Electron shells

Each electron ocupies a discrete energy in state in a given..

2n²

it is a shell can contain a maximum number of electrons given by:

octet rule

A maximum of 8 electrons can exist in the outermost shell of any atom

Binding energy

It is the energy that required to remove a particle completely from the atom

Atomic binding energy

• The energy required to separate an atom into its constituent parts

• It is the sum of the electron binding energy and

  the nuclear binding energy

Nuclear binding energy

• It is the energy necessary to disassociate a

  nucleus into its constituent parts and is the result

  of the strong attractive forces between nucleons

• It is expressed in megaelectron-volts (MeV)

Electron binding energy

• Compared with the nuclear binding energy, the

electron binding energy is negligible

• The closer an electron is to the nucleus, the more

tightly it is bound to its orbit or shell, the higher

the electron binding energy is, and the more

difficult it is to remove the electron from the atom

• The binding energy of electrons in a particular

orbit increases with the number of protons in the

nucleus due to the increase in the positive

charge in the nucleus

• The binding energy of an electron is measured in

a unit called the electron volt (eV)

Atomic mass unit

• amu

• A

• C12

amu

The mass of the particles of an atom is sometimes described using the atomic mass unit for convenience because it is extremely small

A

When precision is not necessary, the mass of an atom is described by an atomic mass no.

C12

one atomic mass unit is one-twelth the mass of a carbon atom

Forces within the atom (3)

• Electromagnetic force

• Strong nuclear force

• Weak nuclear force

Electromagnetic force

The law of electrostatics: like charges repel, opposite charges attract

Strong nuclear force

Holds the nucleus together but operate only iver a very short nuclear distance, thereby creating a nuclear binding energy.

Weak nuclear force

It transforms subatomic particles, from one type into through the radioactive decay

Mass-energy equivalance

binding energy can be calculated by subtracting the mass of the atom from the total mass of its constituent protons, neutrons and electrons; this mass difference is called the mass defect (it represents the energy necessary to hold the nucleus together)

Einstein’s famous equation

E=mc²

Compound and molecules

• Elements are the simplest forms of substances that

compose matter

• Each element is made up of one unique type of atom

with an unchanging number of protons

• Two or more atoms bonded together form a molecule

• A compound is a molecule that contains at least two

different elements

• All compounds are molecules, but not all molecules are

compounds

• It is the chemical bonds between atoms that allow

complex matter to exist

Ionic and covalent bonds

Two types of compounds and molecules

Ionic bond

• based on attraction of opposing charges

• one of the atoms give up an electron and other takes the extra electron

Covalent bond

• base on two atoms sharing electrons that orbit both nuclei

• outermost electron from one atom begins to orbit the nucleus adjacent atom in addition to its original nucleus

Ionization

It occurs when an electron is ejected from a neutral atom, leaving behind a positive ion and thus resulting in one electron-ion pair

Ionizing radiation

Electromagnetic radiation with sufficient energy to eject atomic electrons is called?

Atomic nomenclature: the standard atomic notation

• X

• A

• Z

• N

(Z)

number of protons in the nucleus is the atomic number?

(A)

Total number of protons and neutrons within the nucleus is the atomic mass number (Z+N)

Classifications of nuclides

• Isotopes

• Isotones

• Isobars

• Isomers

Isotopes

whose atoms have the same number of protons but a different number of neutrons

Isotones

whose atoms have the same number if neutrons but different number of protons

Isotones

whose atoms have the same number of neutrons but different number of protons

Isobars

whose atoms have a different number of protons but the same total number of protons and neutrons

Isomers

whose atoms have the same number of protons and neutrons but with different amounts of energy within their nuclei because of how the protons and neutrons are arranged

Ground state

Lowest energy state in excess of the?

Excited state

Nuclei with energy in excess if the ground state are said to be in an?

Periodic table

Based on the atomic number in ascending order and is organized by periods and groups

Nuclear stability

A higher neutron-to-proton ratio is required in heavy elements to offset the coulombic repulsive forces

(X)

Chemical symbol

(N)

Number of neutrons