2.1 Atoms, Isotopes, Ions and Molecules

Chapter 2 Biology

Matter…

Occupies space and has mass

Define what elements are?

Are unique forms of matter with specific chemical and physical properties that cannot be broken down into any smaller substance

What is the smallest unit of matter?

An atom

What are the two regions of an atom called?

Nucleus and Orbitals

What is the nucleus?

Is the center of the atom and contains protons and neutrons

What are orbitals?

Holds the electrons around the nucleus

What symbol is used to refer to a electron?

e^-

What’s considered to be sub-atomic particles?

Protons, neutrons and electrons

What charge do protons have?

+1

What is the charge of a neutron?

0

What is the charge of an electron?

-1

Atomic number is…

The total number of protons

What is atomic mass?

Is determined by the number of protons and neutrons

Define what isotopes are

Different forms of an element that has the same number of protons but a different number of neutrons

What are the isotopes of hydrogen?

Protium, deuterium and tritium

Amu is expressed as…?

Atomic mass units

What are radioisotopes?

Are unstable isotopes that emits neutrons, protons and electrons

What does a neutral charge of an atom mean?

• Number of protons = number of electrons

• Number of electrons = atomic number

How are electron shells/energy levels filled?

Electrons fill orbitals closest to the nucleus then branch out in order (1n, 2n, 3n)

What group on the periodic table have full valence shells?

Group 18

Chemical reactions…

Are changes in distribution of electrons between atoms

Reactants…

Are used in the beginning and typically found on the left side of a chemical equation

Products…

Found at the end of the reaction and usually on the right side of the chemical equation

What is a chemical bond?

The attraction that links atoms together to form molecules and compounds

Chemical formulas…

H₂O and CH₄ gives the number of each type of atom in a molecule

The structural formula…

Shows the arrangement of atoms in a molecule depicted through a diagram

What is a mole?

Is the quantity or amount of a substance

What is the following equation saying:

2H₂O₂ —> 2H₂O + O₂

_{(Hydrogen peroxide) —> (water) + (oxygen)}

Two molecules of hydrogen peroxide produces two molecules of water and one molecule of oxygen

A mole is also known as…?

Also called mol

What is Avogadro’s number?

6.02 × 10²³

Covalent bonds…

Are formed when e^- are shared and a chemical bond is formed

When more than one set of electrons are shared it’s called…

A covalent double bond

When atoms give up or gain electrons this is known as?

Ionic bonds

In ionic compounds…

Metals lose electrons and nonmetals gain electrons to achieve an ocet

Define cations

Positively charged ions that form by losing electrons

Define anions

Negative ions that are formed by gaining electrons

An ion is…

An atom or group of atoms with a positive or negative charge due to an unequal number of protons (+) and electrons (-)

Why is salt a compound?

It consists of more than one type of atom

Polar bonds are…

Covalent bonds when electrons are shared unequally by atoms and are attracted more to one nucleus than the other

Define electronegativity

When an element wants the electrons more than the other one.

Give an example of electronegativity

Oxygen has a higher electronegativity than hydrogen. Meaning it wants the electron more than Hydrogen

What are non-polar bonds?

When electrons are equally shared by the atoms

What bonds require energy to break?

Ionic and covalent bonds

Van der Waals interactions are…

Weaker attractions or interaction between molecules

How do van der waal interactions happen?

When molecules are close in proximity.

What are ionic bonds?

chemical bond that forms between ions with opposite charges (cations and anions)