GB1- Chapter 2 Voab

matter

anything that takes up space and has mass

element

substance that can’t be broken down into other substances through chemical reactions

• makes up matter

compound

substances consisting two or more elements in a fixed ratio

essential elements

20-25% of 92 natural elements

• required for life

• carbon, hydrogen, oxygen, nitrogen make up 96% of living matter (CHON)

• 4% is composed of calcium, phosphorus, potassium, and sulfur (CapKS)

trace elements

elements that are only required in minute quantities

atom

smallest unit of matter that still retains the properties of an element

• makes up element

atomic composition

• atomic nucleus- neutrons and protons

• electrons forming cloud of negative charge

• neutron mass = proton mass/ measured in daltons

• electrons aren’t calculated in atom’s total mass

atomic number

number of protons

mass number

number of protons and neutrons

atomic mass

atom’s total mass

isotopes

atoms of an element that varies in neutron numbers

radioactive isotopes

decay spotaneously, giving off particles and energy

radiometric dating

determines how old a rock or fossil is by measuring the ratios of different isotopes and calculates the number of half lives have passed since its formation

half-life

the fixed rate a parent isotope decays into daughter isotope

can vary from seconds to billions of years

energy

the capacity to cause change

potential energy

energy that matter posesses because of its location or structure

matter has natural tendancy to be at lowest possible potential energy state

electron shells

shells with different energy levels and average distance

valence electrons

in the outermost shell, valence shell

determines chemical behavior of the atom

elements with full valence shells are chemically inert

orbital

3D space where electrons are found 90% of the time

each orbital can have 2 electrons max

atoms interact to complete their valence shells = stability

chemical bonds

formed by the transfer or sharing of valence electrons

covalent bond

equal sharing of a electron pair between atoms

the shared electrons are counted as a part of both atom’s valence shells

molecule

two or more atoms held together by covalent bonds

valence

atom’s bonding capacity

electronegativity

atom’s attraction for electrons in a covalent bond

the more electronegative it is, the stronger it pulls shared electrons toward itself

nonpolar covalent bond

equal electron sharing

polar covalent bond

one atom is more electronegative than the other= resulting in an unfair sharing of electrons

unequal sharing of electrons causes a partial charge

ions

charged atoms

cation

positively charged ion

anion

negatively charged ion

ionic bond

anion and cation’s attraction for each other

ionic compounds/ salts

formed by ionic bonds

NaCl

dissociate easily in water

hydrogen bond

hydrogen atom is bonded to a highly electronegative atom like nitrogen or oxygen

van der waals interactions

weak bonds formed between molecules due to uneven distribution of electrons

• strong collectively

molecule’s shape

determined by orbital positions

covalent bond may cause s and p orbitals to hybridize, creating specific molecular shapes

crucial to molecule function

reactants

starting molecules of a chemical reaction

chemical reactions

making and breaking of chemical bonds

all chemical reactions are reversible

photosynthesis

6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂

products

resulting molecules of a chemical reaction

chemical equilibrium

forward and reverse reactions happening at the same rate

the relative concentration of reactants and products do not change