Chapter 2

Questions :

1. What are the main chemical elements found in body?

First. What is the element? Element is a substance that cannot be broken down to other substances by ordinary chemical means. C,O,H,N - Carbon, Oxygen, Hydrogen, Nitrogen. These are four main elements in our body that form most of the body's compounds, such as: proteins, lipids and etc.... There are as well other elements in our body necessary for our body's functions but because they're in so small amounts we call them trace element, such as Ca, P, K, etc....

2. Why are atoms so important for us?

Atom is the smallest unit of matter that still retains the properties of an element. Atom consists of Nucleus which contains Protons and Neutrons and around the nucleus is Electron cloud. Electrons weight 2000 x less than Neutrons and Protons. But the reason why they are so important is obvious everything living is made up of atoms.

3. What is the difference between covalent and ionic bonds?

Ionic bonds form when the attraction of two ions (ion= atom or molecule with an electrical charge resulting from gain or loss of one or more electrons) holds them together.

Covalent bonds form when 2 atoms or molecules share one or more pairs of outer-shell electrons. So ionic bonds are formed by attraction 2 molecules but covalent bonds are when the molecules share their outer-shell electrons.

Diagram :

Diagram explains the way covalent bonds are created. Molecules connected by a covalent bond share their outer shell electrons to have their outer shell completely full. You can see that H has one non pair outer shell electron but when they connected the free electrons are now in the same shell connected.

5facts :

Elements are rarely found in their pure form. Elements usually form compounds which is a substance consisting of two different elements combined in a fix ratio.

Atoms are the smallest units of matter. They are the basic "building structures" throughout our bodies. They can be also radioactive that happens when they release energy and particles.

Radioactive isotopes can be very helpful. We use them to discover certain types of diseases and also they help us date archeological findings.

Chemical reaction make bonds and break them. Those changes lead to change in a composition of matter. Chemical reactions are obtaining most of the basic functions in our which means that if all chemical reactions would stop our body would stop too.

Hydrogen bonds are very specific for water due to these bonds water have different properties than it'd normally have without them. For example the water doesn't completely freeze in oceans which secures the survival of animals living in water.

Key terms :

pH scale - describes how acidic or basic a solution is. Our blood's pH is 7.4

acid - acidic solution have bigger amount of H+ than neutral solution

base - basic solution contains more OH- ions than neutral solution

solvent and solute - the dissolving agent is the solvent and the substance being dissolved is solute

element - substance that can't be broken down to other substances by ordinary chemical means

matter - everything is composed of matter, which is anything that occupies space and has mass

trace elements - elements found in body that are essential but are in a minute quantities

compound - substance consisting of two or more elements combined in fixed ratio

ion - is an atom or molecule with an electrical charge resulting from a gain or loss of one or more electrons

chemical bond - is when two atoms complete their outer shell

Video:

Covalent bond

Summarize :

Chapter 2 describes elements, atoms and molecules. Also the difference between chemical bonds and their characteristics. Also a big part of this chapter talked about water and its specific characteristic such as: cohesion and adhesion, hydrogen bonds (very typical for water) and etc.... It also described pH scale and what this scale represents.