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Bromothymol blue is an indicator that turns blue in a base, or yellow in acid. Made with special chemical compounds that react slightly with an acid or base,

The physical properties of acids and bases are opposites.

base.

Acids will react with bases to form a salt and water. This is a neutralization

reaction. The products of a neutralization reaction are much less acidic or basic than the reactants were. For example, sodium hydroxide (a base) is added to hydrochloric acid.

This is a double replacement reaction.

Acids
Acids react with metal to

produce a metal salt and hydrogen

gas bubbles.
Acids react with metal

carbonates to produce water, CO₂ gas

to produce water and a salt.

As scientists are not able to visit the Earth’s deep interior or place instruments within it, they explore in subtle ways. One approach is to study the Earth with non-material probes, such as seismic waves emitted by earthquakes. As seismic waves pass through the Earth, they undergo sudden changes in direction and velocity at certain depths. These depths mark the major boundaries, also called discontinuities, that divide the Earth into crust, mantle and core.

The Crust. The Earth’s crust is the thin outermost layer of the Earth, with an average depth of 24 km (15 mi). The crust accounts for 1.05% of the Earth’s volume and 0.5% of its mass. The chemical elements oxygen, silicon and aluminum dominate the crustal composition. The major mineral type – the feldspars – are alumino-silicates of the alkali and alkaline-earth metals. Silicon dioxide is the second most

As we celebrate Earth Day, and as in recent times, emphasis has been given to environmental awareness or the value of “green.” This year, let’s pay attention to all the other colors of Earth as well – the colors we see through chemistry.

Carbon: Introduction

Atomic Number: 6
Electronic configuration: 2, 4

Valence electrons: 4

Property: Non-metal

Abundance: Carbon is the 4th most abundant substance in universe and 15th most abundant substance in the earth’s crust.

Bond formed by sharing of electrons is called covalent bond. Two of more atoms share electrons to make their configuration stable. In this type of bond, all the atoms have similar rights over shared electrons. Compounds which are formed because of covalent bond are called COVALNET COMPOUNDS.

Covalent bonds are of three types: Single, double and triple covalent bond.

Single Covalent Bond: Single covalent bond is formed because of sharing of two electrons, one from each of the two atoms.

Formation of hydrogen molecule (H₂)

Valence electron of H = 1

Formation of hydrogen chloride (HCl):

Valence electron of hydrogen = 1

Atomic number of chlorine = 17

Electrons in outermost orbit = 7

Formation of chlorine molecule (Cl₂):

Formation of water (H₂O)

Atomic number of oxygen = 8

Electronic configuration of oxygen = 2, 6

Valence electron = 6

Oxygen in water molecule completes stable configuration by the sharing one electron from each of the two hydrogen atoms.

Formation of Methane (CH₄)
Valence electron of carbon = 4

Valence electron of hydrogen = 1

Formation of Ethane (C₂H₆):

Double covalent bond: Double bond is formed by sharing of four electrons, two from each of the two atoms.

In the formation of oxygen molecule, two electrons are shared by each of the two oxygen atoms to complete their stable configuration.

Formation of Carbon dioxide (CO₂):

Valence electron of carbon = 4

Valence electron of oxygen = 6

In carbon dioxide two double covalent bonds are formed.

Formation of Ethylene (C₂H₄):

Valence electron of carbon = 4

Atomic number of nitrogen = 7

Electronic configuration of nitrogen = 2, 5

Valence electron = 5

In the formation of nitrogen, three electrons are shared by each of the nitrogen atoms. Thus one triple bond is formed because of the sharing of total six electrons.

• 
  Intermolecular force is smaller.
  
• 
  Covalent bonds are weaker than ionic bond. As a result, covalent compounds have low melting and boiling points.
  

• 
  Covalent compounds are poor conductor of electricity as no charged particles are formed in covalent bond.
  

• 
  Since, carbon compounds are formed by the formation of covalent bond, so carbon compounds generally have low melting and boiling points and are poor conductor of electricity.
  

5.1 Biochemistry, sometimes called biological chemistry, is the study of chemical processes within and relating to living organisms.^[1]By controlling information flow through biochemical signaling and the flow of chemical energy through metabolism, biochemical processes give rise to the complexity of life. Over the last decades of the 20th century, biochemistry has become so successful at explaining living processes that now almost all areas of the life sciences from botany to medicine to genetics are engaged in biochemical research.^[2] Today, the main focus of pure biochemistry is on understanding how biological molecules give rise to the processes that occur within living cells,^[3] which in turn relates greatly to the study and understanding of tissues, organs, and whole organisms^[4]—that is, all of biology.

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Biochemistry focuses on processes happening at a molecular level. It focuses on what’s happening inside our cells, studying components like proteins, lipids and organelles. It also looks at how cells communicate with each other, for example during growth or fighting illness. Biochemists need to understand how the structure of a molecule relates to its function, allowing them to predict how molecules will interact.

Biochemistry covers a range of scientific disciplines, including genetics, microbiology, forensics, plant science and medicine. Because of its breadth, biochemistry is very important and advances in this field of science over the past 100 years have been staggering. It’s a very exciting time to be part of this fascinating area of study.