MS - PS1A - Structure of Matter - FINAL (CLF 1-8-2014)

DCI: PS1.A (A) Substances are made from different types of atoms, which combine with one another in various ways.  Atoms form molecules that range in size from two to thousands of atoms.

DCI: PS1.A (E) Solids may be formed from molecules, or they may be extended structures with repeating subunits (e.g., crystals).

PE: MS-PS1-1 Develop models to describe the atomic composition of simple molecules and extended structures.

 [Clarification Statement: Emphasis is on developing models of molecules that vary in complexity. Examples of simple molecules could include ammonia and methanol. Examples of extended structures could include sodium chloride or diamonds. Examples of molecular-level models could include drawings, 3D ball and stick structures, or computer representations showing different molecules with different types of atoms.] [Assessment Boundary: Assessment does not include valence electrons and bonding energy, discussing the ionic nature of subunits of complex structures, or a complete description of all individual atoms in a complex molecule or extended structure is not required.]

The ideas we see in this standard are: 

- substances are made of different types of atoms

- atoms combine with one another in various ways

- atoms form molecules

- molecules can be made up of as few as two or many thousands of atoms

- solids can be formed from molecules

- solids may be formed from extended structures

This is definitely not a protons, neutrons, electrons standard.  It doesn't look like we will be asking kids to tell us how many particles of each atom in a chemical formula.  Instead, they should know that some molecules are very simple and others are quite complex.  There is a lot of content within the DCIs.  

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an ordered pattern extending in all three spatial dimensions. In addition to their microscopic structure, large crystals are usually identifiable by their macroscopic geometrical shape, consisting of flat faces with specific, characteristic orientations.

Possible Question Starters:

"Some students drew the following diagram to represent a substance composed of hydrogen and oxygen. Which of the following is true about this substance? "

correct answer - this is just one of many ways in which hydrogen and oxygen can combine 

incorrect answer - two atoms of hydrogen are always required to bond with two atoms of oxygen