Journey into the depth of sucrose crystal

Video 1

Learning Outcomes:

At the end of the lesson the students should be able to:

1. identify and describe the matter, classification of matter, proton, electrons and neutrons as sub-atomic particles.

2. define proton number, nucleon number, relative atomic mass and relative molecular mass

3. define and describe isotopes.

MatterAnything that occupies space and possesses mass is

called matter. • Example: air, earth, animals, trees, atoms,…• The three states of matter are solid, liquid and gas

Three States of Matter

SOLID LIQUID GAS

Mixtures

has one or more visible boundaries between the components.

has no visible boundaries because the components are mixed as individual atoms, ions, and molecules.

A homogeneous mixture is also called a solution. Solutions in water are called aqueous solutions, and are very important in chemistry. Although we normally think of solutions as liquids, they can exist in all three physical states.

Heterogeneous mixtures :

Homogeneous mixtures :

Solutions :

Compound - a substance

composed of two or more

elements which are

chemically combined.

Mixture - a group of two or more elements and/or compounds that are physically intermingled.

Definitions for Components of Matter

Mixtures and Compounds

S

Fe

Physically mixed therefore can be separated by physical means.

Allowed to react chemically therefore cannot be separated by physical means.

Definitions for Components of Matter

Element - the simplest type of substance with unique physical and

chemical properties. An element consists of only one type of atom.

It cannot be broken down into any simpler substances by physical

or chemical means.

Molecule - a structure that consists of two or

more atoms which are chemically bound

together and thus behaves as an independent

unit.

ATOM• An atom is composed of three kinds of

elementary subatomic particle: electrons, protons and neutrons.

• Protons and neutrons form the atomic nucleus.

• Electrons can be thought of as forming negatively charged clouds around the nucleus.

Ernerst Rutherford (1871 – 1937)New Zealander-English physicist who was bornin Nelson, New Zealand. Rutherford is best knownfor devising the names alpha, beta and gammarays to classify various forms of "rays" which were poorly understood at his time.

Modern Model of the Atom

DEFINITION

• Proton number :

A number of protons in the atomic nucleus

• Nucleon number :

The number of nucleon (protons and neutrons) in the atomic nucleus.

The Modern Reassessment of the Atomic Theory

1. All matter is composed of atoms. The atom is the smallest body that retains the unique identity of the element.

2. Atoms of one element cannot be converted into atoms of another element in a chemical reaction. Elements can only be converted into other elements in nuclear reactions.

3. All atoms of an element have the same number of protons and electrons, which determines the chemical behavior of the element. Isotopes of an element differ in the number of neutrons, and thus in mass number. A sample of the element is treated as though its atoms have an average mass.

4. Compounds are formed by the chemical combination of two or more elements in specific ratios.

Video 2

Proton number and nucleon number

• A: nucleon (mass) number (Z+n)• Z: proton (atomic) number• X: chemical element symbol

Video 3Video 4

Example 1.1.2Give the number of protons, neutrons and electrons in each of the

following species: (a) (b)

(c) (d)

+3243227

-21098

0293429

08012080

electronneutronproton

ChargeNumber ofSymbol

Hg20080

Cu6329

2178O

35927Co

Hg20080 Cu63

29217

8O359

27Co

Note:The proton number, Z, is the nuclear charge and also the number of electrons in a neutral atom of the element.no. p = no. e atom (neutral)no. p > no. e positively charged – cation (atom lost electrons)no. p < no. e negatively charged – anion (atom gained electrons)

Isotopes

Notes:Isotopes of an element have the same, - number of protons (proton number) - charge of nucleus of the atoms (ionization energy; electron affinity; size of the atom; electronegativity are the same)- number of electrons in a neutral atom - electronic configuration (the number of valence electrons)- chemical propertiesIsotopes of an element have different, - number of neutrons (nucleon number) in the nucleus of the atoms - relative isotopic mass - physical properties (e.g boiling point / melting point, density, effusion rate,…)

Video 5

Isotope = atoms of an element with the same number of protons, but a different number of neutrons

Relative atomic and molecular mass

Relative Atomic Mass, Ar of an element

Ar = average mass of one atom of the element

1/12 x mass of one atom of 12C• The average relative isotopic mass of the atoms

must be used for calculation because most elements consist of a mixture of isotopes.

Notes: Ar and Mr – dimensionless Molecular mass, atomic mass – atomic mass unit (amu)

Video 6

Relative Molecular Mass, Mr of a molecular substanceMr = average mass of one molecule of the substance

1/12 x mass of one atom of 12C or

= sum of the relative atomic masses of all the atoms shown in the molecular formula.

Example: Mr of H2O = 2 (Ar of H) + Ar of O

= 2(1.008) + 15.999 = 18.15

relative molecular mass of CaCl2 = 40 + 2(35.5) = 111relative molecular mass of SO4

2 = 32 + 4(16) = 96

Determining the number of atomic constituents

Atom Ion

Video 7 Video 8

Exercise 1.1Complete the symbols for the following elements

and fill in the blanks in the table.

Radioisotopes

• Radioisotopes have a number of important applications beyond the production of energy or weapons of mass destruction.

- neutron activation analysis

- geological dating

- tracers

- oncology

- radiation detection

Video 9

Conclusion

At the end of the lesson the students should be able to:

1. identify and describe the matter, classification of matter, proton, electrons and neutrons as sub-atomic particles.

2. define proton number, nucleon number, relative atomic mass and relative molecular mass

3. define and describe isotopes.