Biology Lab Chemistry of Life (Silva 1406)

What forms the atomic number of an element

Number of protons of an atom

What forms the atomic mass of an element

protons + neutrons of an atom

Electrons is equal to ______

the number of protons in an atom

Where are protons and neutrons located

nucleus

where are electrons located

electron cloud

What are the charges of

• Protons

• Electrons

• Neutrons

• +1

• -1

• 0

What is matter

Anything that has mass and occupies space

Isotopes

atoms of the same element but different number of neutrons

Ions

atoms with a charge as a result of losing or gaining an electron

• Cation for positive charge

• Anion for negative charge

Dmitri Mendeleev

made the first periodic elemnts and used the periodic law

Periodicity

similar characteristics between elements

Group Number

# of electrons in the valence shell of an element

Period number

number of shells of electrons around an atom’s nucleus

Valence shell

outermost shell of electrons in an atom

Number of electrons needed to stabilize and fill a valence shell

8 except for Hydrogen which just needs 2

Importance of valence

Allows the formation of molecules and compoinds

Does valency mean reactivity?

Yes

Element with 5,6, or 7 valence electrons tend to

gain electrons

Elements with 1,2, or 3 valence electrons tend to

lose electrons

Ionic bonds

Bonds between atoms where electrons are lost and gained

Covalent Bonds

sharing of electrons between 2 electrons

• Polar- Unequal sharing of electrons

• Non-Polar- Equal sharing of electrons

Most common elements for life

• Carbon

• Hydrogen

• Oxygen

• Nitrogen

Elements important for plants

• Nitrogen

  • needed to make chlorophyll and plant proteins

• Phosphorus

  • to make ATP and nucleic acids

• K (Potassium) (Potash)

  • Protein synthesis, plant growth, and photosynthesis

pH

scale that measures concentration of H⁺ protons in an solution in a negative log

pH of below 7

Acids

pH of 7

neutral pH

pH of above 7

alkaline/bases

Acid releases ______ in a solution

H⁺ protons

Base releases _______in a solution

OH^-

What pH range do most chemical reactions in humans occur

7.35-7.45

What pH range are plants best adapted to

5-6.5 pH

Compounds that release neither H⁺ or OH^- into a solution

salts