Elements, Compounds, Molecules and Subatomic

particles

Kashish S, Kalika P and Paranshi Z

Contents • Elements • Compounds• Molecules • Subatomic particles (protons,

neutrons, and electrons) • Quiz

Elements • ELEMENT is a substance consisting of atoms

which all have the same number of protons - i.e. the same atomic number.

• Although an element's atoms must all have the same number of protons, they can have different numbers of neutrons and hence different masses. When atoms of the same element have different numbers of neutrons, they are called isotopes.

Compounds • COMPOUND is a combination of 2 or more

elements in definite ratios by mass. • The character of each element is lost when

forming a compound (e.g., think of NaCl).

Difference betweenCompounds

• A compound contains atoms of different elements chemically combined together in a fixed ratio.

• A compound is represented using a formula.

• The list of compounds is endless.

Elements• An element is a pure

chemical substance made of same type of atom.

• An element is represented using symbols.

• There are about 117 elements that have been observed. Can be classified as metal, non-metal or metalloid.

Molecules • MOLECULES are the smallest units of a

compound that retains the characteristics of the compound.

• The smallest particle of a substance that retains the chemical. A group of like or different atoms held  together by chemical forces.

Subatomic particles• The three main subatomic

particles that form an atom are protons, neutrons, and electrons. The center of the atom is called the nucleus.

Neutrons • Neutrons, with protons and electrons,

make up an atom. Neutrons and protons are found in the nucleus of an atom. Unlike protons, which have a positive charge, or electrons, which have a negative charge, neutrons have zero charge. Neutrons bind with protons. Neutrons were predicted by Ernest Rutherford, and discovered by James Chadwick, in 1932.

Electron• Electron is a very small piece

of matter and energy. Its symbol is e−. The electron is a subatomic particle. It is believed to be an elementary particle because it cannot be broken down into anything smaller. It is negatively charged, and may move almost at the speed of light.

Proton • Proton is part of an atom. They are found in

the nucleus of an atom along with neutrons. The periodic table groups atoms according to how many protons they have. A single atom of hydrogen is made up of an electron moving around a proton. Most of the mass of this atom is in the proton, which is almost 2000 times heavier than the electron. Protons and neutrons make up the nucleus of every other kind of atom.

QUIZ

Q1) Carbon Dioxide Is Made Up Of A Carbon Atom And 2 Oxygen Atoms.

What Is It’s Formula?

• CO2

• Carbon dioxide is a colorless, non-organic compound that is a gas at room temperature and comprises about 0.03 percent of Earth's atmosphere.

Q2) What Is The SI Unit For Atomic Mass

• AMU (atomic mass unit)

• An atomic mass unit is defined as precisely 1/12 the mass of an atom of carbon-12. The carbon-12 (C-12) atom has six protons and six neutrons in its nucleus.

Q3) State One Difference Between Element And Compound

• A compound is represented using a formula.

• An element is represented using symbols.

Q4)After seeing the image tell the name of the following element :

• Na • Sodium• Cl• Chlorine• K• Potassium