Lesson 1 - Introduction to Chemistry

What is the atomic number for Hydrogen, Carbon, Nitrogen , Oxygen

1, 6, 7, 8

Atomic number = Number of electrons =

Number of protons

Atomic mass =

number of protons and neutrons

Isotopes is an element with the same atomic number but a …

different mass, differnt number of neutrons

This serves as a passage of electrons around the nucleus

Electron Shell

The inner shell can accomodate at most __ electrons

2

The outer shells can accomodate _____ electrons per shell

8

Molecules are formed by combination of

Atoms

In molecules, atoms are joind together by

Chemical bonds

If the outer most shell is full it ______ form chemical bonds

Cannot

If the outer most shell is NOT full it ______ form chemical bonds

Can

Inert gasses _____

Do not form chemical bonds

What is the strongest chemical bond?

Covalent bonds

What is the second strongest chemical bond?

Ionic Bonds

What is the weakest chemical bond?

Hydrogen bonds

In this bond, the atoms share the outer elctrons to form a stable bond

Covalent bond

In non polar covalent bonds, atoms are attraced by….

Equal Forces

In polar covalent bonds, there is an ___________ between atoms, creating small charges

Unequal Pull

A water molecule is made via a

polar covalent bond

An electron moving from one shell (becomes positive) of an atom into the outer shell of another atom (becomes negative) is

An example of an ionic bond (there is an attraction due to electric charges from an ionic bond)

A slightly positive hydrogen of polar molecule is attracted to slightly negative atom ____

An example of hydrogen bond

Polar-covalent bond is found ____ a water molecule

Within

Hydrogen bonds are found _____ water molecules

Hydrogen bonds

Hydrogen bonds make water molecules “stick together”. This is an example of

Cohesion

Cohesion gives water ____

Surface tension, net-like properties

Heat from the sun ____ rather than increasing water temperature

rearranges hydrogen bonds

Water, when solid, has ____

Low density

This is a liquid that dissolves other substances

Solvent

This substance gets dissolved in a solvent

Solute

This is a mixture of solute and solvent

Solution

In hydrophilic, molecules with _____ dissolves in water

Charges (e.g. salt, sugar), ionic and polar bonds

Non-polar molecules do not dissolve in water. This is …..

Hydrophobic

Ok got it water

In ionization fo water, pure water contains an _______ of OH- and H+ ions

Equal amount

pH is an indicator of ______ in solution

H+ ions

The more H+ than OH-, the more

Acidic (reactive, sour)

The more OH- than H+ ions, the more __

Basic (caustic/burning to skin, slippery & bitter)