atoms and bonds

what is an atom

an atom is the smallest unit of an element that retains the chemical properties of that element

what are the three main subatomic particles

protons (+ charge), neutrons (no charge), electrons (- charge)

where are protons and neutrons found

in the nucleus of the atom

where are electrons found

in electron shells/orbitals surrounding the nucleus

what charge does a proton have

a positive (+1) charge

what charge does an electron

a negative (-1) charge

what is the atomic number

the number of protons found in the nucleus of an atom

what is an isotope

atoms of the same element with different numbers of neutrons

why are isotopes useful in healthcare

they are used in medical imaging, diagnosing, and cancer treatments

what is chemical bonding

the attraction between atoms that allows them to form molecules or compounds

what is an ionic bond

a bond formed by the transfer of electrons from one atom to another

what happens to atoms after ionic bonding

they become ions because they gain or lose electrons

give an example of ionic bonding

sodium transfers an electron to chlorine, forming sodium chloride (NaCI)

why are ionic bonds strong

because opposite charges attract strongly

what is a covalent bond

a bond formed when atoms share electrons

why are covalent bonds important in the body

they hold together biological molecules such as proteins, carbohydrates, lipids and DNA

what is a hydrogen bond

a weak attraction between a partially positive hydrogen atom and another electronegative atom

why are hydrogen bonds important in water

they give water its unique properties, including cohesion and high heat capacity

what does hydrophilic mean

'‘water-loving’ substances that interact well with water

give examples of hydrophilic substances

sugar, salt, and the heads of phospholipid molecules

what does hydrophobic mean

‘water-fearing’ substances that do not mix well with water

give examples of hydrophobic substances

oils, fats, waxes, and phospholipid tails

why is water called a polar molecule

because electrons are shared unevenly, creating partial positive and negative regions

what property of water helps transport substances in the body

its ability to act as a solvent

why is water important for temperature regulation

water has a high heat capacity, so it absorbs heat without rapid temperature changes

what is cohesion

the attraction of water molecules to each other through hydrogen bonding

what is adhesion

the attraction of water molecules to other substances

what is pH

a measure of hydrogen ion (H+) concentration in a solution

what does a low pH indicate

a high concentration of hydrogen ions and an acidic solution (<7)

what does a high pH indicate

a low concentration of hydrogen ions and a basic (alkaline) solution (>7)

what do acids do

release hydrogen ions (protons)

what do bases do

accept hydrogen ions (protons)

why is pH important in the body

changes in pH affect enzyme activity, ion balance, and normal cell function

what is a buffer

a substance that resists changes in pH by accepting or releasign hydrogen ions

why are buffers important in the body

they help maintain a stable internal environment

what is the normal pH range of blood

7.35-7.45

what is acidosis

a condition where blood pH falls below the normal range

why can acidosis be dangerous

it can disrupt organ function and may be life-threatening

what makes a good biological buffer

water soluble, non-toxic, doesn’t interfere with biological processes

which body systems help maintain pH

respiratory system, kidneys, and blood buffer systems

how do the lungs help regulate pH

by controlling carbon dioxide levels through breathing

how do the kidneys help regulate pH

by excreting hydrogen ions and reabsorbing bicarbonate

why is maintaining pH homeostasis important

because enzymes and cells function best within a narrow pH range