Answer :
1. In the world of science, there are 2 kinds
of changes that happen in a substance. The physical and the chemical.
Now, let’s differentiate the two Physical change happens when the physical mass and texture of a certain thing changed without changing the chemical state of the said thing. While chemical change happen when the chemical of the substance change even without changing its physical state.
Physical state happen for example: If a water will be put in the freezer, the water will be frozen and become solid, the physical state of the water changes but the nothing happened in the chemical.
Now, let’s differentiate the two Physical change happens when the physical mass and texture of a certain thing changed without changing the chemical state of the said thing. While chemical change happen when the chemical of the substance change even without changing its physical state.
Physical state happen for example: If a water will be put in the freezer, the water will be frozen and become solid, the physical state of the water changes but the nothing happened in the chemical.
A substance is defined by its composition and structure (chemical bonds).
The composition is the ratio of the amount of each kind of atoms in the chemical formula, and the structue is how the atoms are bonded to each other.
Physical properties change when physical changes occurs: a deformation (change of form), a change of phase (e.g. melting or boiling), a separation (e.g. filtration or distilation) are changes of the appearance of the substance. But this kind of changes does not modifiy the composition and structure of the substance, so the substance remain being the same.
On the other hand, chemical properties are those that are observed when a substance ungergoes a chemical change (reaction). During the chemical reaation some chemical bonds will be broken and other will be formed, which will lead to one or more new different substances. Those different substances will have different structures and compositon than the original substance.
The reactant substances change and become the product substances, which, as said, have different composition (proportion of atoms).