Match the following terms and definitions. 1.the smallest unit of an element atom 2.the path surrounding the nucleus of an atom in which electrons are normally located molecule 3.the number of protons in the nucleus of the atom proton 4.a pure substance where atoms of two or more elements are chemically bonded to one another shell 5.the positively charged center of an atom nucleus 6.exists in orbit around the nucleus of an atom and carries a negative charge neutron 7.the smallest unit of a pure substance that consists of two or more atoms held together by a chemical bond electron 8.the mass of an element diatomic 9.a subatomic particle that carries no charge compound 10.containing two atoms atomic number 11.a subatomic particle with a positive charge atomic mass

1. the smallest unit of an element : atom

2. the path surrounding the nucleus of an atom in which electrons are normally located : shell

3. the number of protons in the nucleus of the atom: atomic number

4. a pure substance where atoms of two or more elements are chemically bonded to one another: compound

5. the positively charged center of an atom:  nucleus

6. exists in orbit around the nucleus of an atom and carries a negative charge:  electron

7. the smallest unit of a pure substance that consists of two or more atoms held together by a chemical bond : molecule

8. the mass of an element: atomic mass

9. a subatomic particle that carries no charge : neutron

10. containing two atoms : diatomic

11. a subatomic particle with a positive charge : proton

Explanation: An atom is the smallest unit of the matter and contains neutrons, protons and electrons as subatomic particles. Neutrons which are neutral and protons which are positively charged are present in the nucleus and the electrons which are negatively charged revolve around the nucleus called as shells.

Element is a pure substance which is composed of atoms of similar elements. Molecule of a Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.  Example:

Molecule of an element is a pure substance formed by combination of same types of atoms bonded by a chemical bond. Example:

The number of protons present in the nucleus of an atom is defined as the atomic number and is characteristic of a particular element.

The number of protons and neutrons collectively contribute to the mass of the element and is called as atomic mass.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!