and Answers
the body's cells, tissues, and organs are - ✅✅all composed of chemicals and function through
chemical reactions
chemistry is the science - ✅✅that studies the elements, their compounds, the chemical reactions that
occur between elements and compounds, and the molecular structure of all matter
atoms - ✅✅are the smallest particles of elements that maintain all the characteristics of that element
and enter into chemical reactions through their electrons
an atom - ✅✅consists of a nucleus containing positively charged protons and neutral neutrons
electrons - ✅✅have a negative charge and orbit the nucleus of an atom in levels at some distance
from the compact heavy nucleus
element - ✅✅is a substance whose atoms all contain the same number of protons and the same
number of electrons;
atoms - ✅✅are electrically neutral
compound - ✅✅is a combination of the atoms of two or more elements
isotope - ✅✅is a different kind of atom of the same element where the number of neutrons in the
nucleus variess
carbon - ✅✅is the element found in all living matter
periodic table of elements - ✅✅arranges elements in categories with similar properties
, atoms combine chemically with one another to - ✅✅form bonds by gaining, losing, or sharing
electrons.
ionic bond is formed - ✅✅when one atom gains electrons while the other atom in the bond loses
electrons; while the other atom in the bond loses electrons; ionically bonded molecules disassociate
when immersed in water. The mineral salts form ionic bonds.
Covalent bond is formed - ✅✅when atoms share electrons; Carbon, oxygen, hydrogen, and nitrogen
form covalent bonds. These bonds do not dissociate when placed in water
Hydrogen bonds are - ✅✅weak bonds; they help hold water molecules together and bind other
molecules into three-dimensional shapes
Molecules furnishing electrons during a chemical reaction - ✅✅are called electron donors; those that
gain electrons are called electron acceptors
Bonds contain - ✅✅energy; these are the electrons that contain the energy of a chemical bond
special molecules called electron carriers - ✅✅accept electrons for a short period of time and use the
energy of the electrons to make ATP molecules
10 common substances found in living systems are - ✅✅water, carbon dioxide, oxygen, ammonia,
mineral salts, carbohydrates, lipids, proteins, nucleic acids and adenosine triphosphate
water - ✅✅60% to 80 % of a cell is water (H2O)
water is a slightly polar molecule - ✅✅the two hydrogen atoms have a partial positive charge and the
oxygen atom a partial negative charge; explains why ionically bonded molecules dissociate when placed
in water