Notes, abstracts, papers, exams and problems of Chemistry

The Law of Conservation of Mass

Matter cannot be created or destroyed. The number of atoms in the reactants must be the same as the products. Atoms don't appear or disappear, they just rearrange. (Hence why you have to balance out chemical equations)

Balancing Equations

• The subscripts in the chemical formula cannot be changed (The little number beside a formula that is part of it).
• Use coefficients to balance.
• Coefficients multiply the entire compound by that number (4PO = 4P 4O).

Example: N₂+O₂>N₂O = 2N₂+O₂>2N₂O

Balancing Word Equations

• Determine what the reactants and the products are, convert names to chemical formulas. (Individual elements that are diatomic (molecular) will be, S₈, P₄, I₂, Br₂, Cl₂, F₂, O₂, N₂, H₂) If it's not diatomic just

Structure of the Atom

Protons, Electrons, and Neutrons

Protons: Equal to the atomic number

Electrons: Equal to the atomic number

Neutrons: Equal to the atomic mass minus the atomic number

Bohr-Rutherford Diagram

Electron shells: 2, 8, 8, 18, 18, 32

Counting Atoms

Example 1: Na₂CO₃

• Sodium (Na): 2
• Carbon (C): 1
• Oxygen (O): 3

Example 2: 4Al₂(CO₃)₃

• Aluminum (Al): 4 x 2 = 8
• Carbon (C): 3 x 4 = 12
• Oxygen (O): 9 x 4 = 36
• Total: 56

Ions and Ionic Compounds

Ions are atoms that have either lost or gained electrons. While atoms are neutral, ions are charged particles.

Ionic Compounds are a combination of a cation (positive ion) and an anion (negative ion), typically formed between a metal and a nonmetal.

Example: Calcium Chloride (CaCl₂)

Calcium (Ca⁺²) has a charge of +2,... Continue reading "Structure of the Atom, Chemical Reactions, and Acids and Bases" »

pure substance: is a phase of uniform composition and unchanging can not be decomposed into other substances of different classes by physical methods.

elements: they are pure substances that can not be decomposed into simpler ones through normal chemical processes.

compounds: they are pure substances made up of two or more elements, which can be decomposed by chemical methods on the elements of which are constituted. A compound always has the same elements and the same proportions regardless of the process followed.

Blended is an aggregation of different substances without causing any chemical reaction between them and therefore may be separated by physical methods.

ponderal laws: they refer to the quantity of matter of different substances... Continue reading "Laws ponderal" »

5. Describe what is electrodeposition, describe the different Experimental methods. Give examples. Advantages and disadvantages. It is the process of production a coating, usually Metallic, on a surface by the action of an electric current._Experimental Methods::-Electroplating: It is a plating process in which metal ions in a Solution are moved by an electric field to coat an electrode. Metallic cations From a solution are reduced on a conductive object (to form a thin layer).-Electrophoretic Deposition:Colloidal particles suspended in a liquid migrate under the Influence of an electric field (electrophoresis) and are deposited onto an Electrode._Advantages: uniform coating thicknen,easy control,high speed of Coating and high pucity._Disadvantages:

Anhydrides:

Non metal + O2 = Systematic Nomenclature / IUPAC (Anhydride)

Acids / Oxoacids:

Acids + H2O = IUPAC (Acid)

Basic Oxoacids:

Metal + O2 = Stock Nomenclature (nº) / IUPAC (Oxide)

Hydroxides:

Basic Oxide + H2O = IUPAC (Hydroxide)

Salts:

Hydroxide + Acid (ic - ate / ous - ite) Fe(OH)2 + HClO = Fe(ClO)2 - Ferrous Hyperchlorite

• Hypo - ous
• - ous
• - ic
• Hyper - ic

Stoichiometry:

Law of Conservation of Mass

Mole:

Amount of Substance that Contains as Many Particles (g)

Molar Mass:

1 mol of --- / g of ----

The environment plays an important role in our lives and people wouldn't be able to live without it. However, we are polluting it every day and it needs to stop. As individuals, we can do lots of things to solve this issue, and this essay will focus on two of them - recycling and the efficient use of energy.

According to recycling, it is the easiest way to see an immediate change and everybody can do it. First, recycling bins are a great method of dividing our waste into paper, plastic, glass, etc., and they can be easily found in every city. Another idea is to reuse the things we have at home and make them new. For example, turning …. 

When it comes to the use of energy, there are many things we can do, especially at home. When we talk about... Continue reading "I choose to live" »

Q#6.3: Define (i) Crystal lattice (ii) Unit Cell.

Ans.(i) Crystal Lattice.

A particular three-dimensional arrangement of particles (atoms, ions, molecules) in a crystal is called a crystal lattice.

In a crystal lattice, particles are located at definite positions in space. These positions are represented by points in a crystal and are called lattice points or lattice sites. This arrangement is called a crystal lattice or space lattice. A crystal lattice actually shows the shape of a crystal.

(ii) Unit Cell.

The smallest geometrical portion of the crystal which is used to build up the whole crystal. OR

If is the smallest portion of a crystal lattice which includes all the positions of each type of particle in the crystal. For example, a cubic crystal... Continue reading "Crystal Lattice and Unit Cell" »

H-hydrogen  2 BE-beryllium    3  B-boron     4 ca-carbon       5n-nytrogen

LI-lithium      MG-magnesium  Ai-aluminium si-silicon         p-phosphorus

na-sodium     CA-calcium        ga-gallium    ge-germanium as-arsenic

CS-cesium      bA-barium        in-indium      se-tin               sb-antimony

FR-francium   RA-radium        ti-thallium      pb-lead            bi-bismuth

6o-oxygen    7 f-fluorine     8 he-hellium        maass(m)   current intensity(iv)

s-sulfur         ci-chlorine        ne-neon          length(l)      surface area(s)

se-selenium  br-bromine      ar-argon         ... Continue reading "What is the time of the pet" »

An ion is an atom which has more or less electrons than protons

C

Circumnavigate

To sail or travel all the way around.

Citadel

A fortress defending a city.

Clandestine

Concealed or secret for an evil purpose.

Classic

Of the highest quality.

Cleave

To cling.

Climatic

Having to do with the climate.

Cloister

Covered walk, with columns on one side.

Clone

An exact duplicate.

Clout

A blow.

Cloy

To cause to feel too full when eating; overly sweet.

Coddle

To baby.

Cogitate

To ponder.

Cohort

A group.

Commemorate

To honor the memory of.

Commiserate

To express sorrow or sympathy for.

Commodious

Spacious, roomy.

Compatible

Harmonious.

Competent

Capable.

Compile

To gather together.

Comply

To act or be in accordance with.

Composed

Calm.

Compromise

A settlement of differences in which each side gives up something.

Compunction

Remorse.

Concave

Curved inward.

Concede

To