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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