Science Notes: Test Questions Flashcards
How can matter made of the same substances look so different?
The way atoms are arranged and bonded in a substance changes its appearance and properties, even if it’s made of the same elements.
Name the subatomic particles.
Subatomic particles include protons (positive charge), neutrons (no charge), and electrons (negative charge).
How is the periodic table of elements organized and what do the numbers mean?
The periodic table is arranged by increasing atomic number (number of protons).
The other important number is the “Atomic Mass” (it is the number with the decimal like 51.0) and is the average weight of the nucleus, with minor contributions from the electrons.
What is the difference between physical and chemical properties?
Physical properties can be observed without changing the substance (e.g., color, melting point).
Chemical properties describe how a substance reacts and changes into a new substance (e.g., flammability).
How can we tell if a chemical reaction has occurred?
Signs include color change, gas bubbles, a temperature change, a new solid forming (precipitate), or light being produced.
But the only way to know for certain is if the reactants rearrange to create different substances as products.
How can an unknown substance be identified using physical and chemical properties?
Measure its physical properties like density or melting point, and test its chemical reactions, such as how it reacts with acids or oxygen.
What are synthetic materials, and how are they different from natural materials?
Synthetic materials are man-made, like plastic, while natural materials are found in nature, like wood.
What steps are taken to create a synthetic material?
Scientists combine raw materials in labs or factories, using chemical processes to make something new, like refining oil to make plastic.
Is it better to use synthetic materials or natural resources?
Both have pros and cons. Synthetic materials last longer and can be made in large quantities, but natural materials are often more eco-friendly.
What happens to atoms during a chemical reaction?
Atoms rearrange to form new substances, but no atoms are created or destroyed.
What are the signs of a chemical reaction?
Signs include color change, gas bubbles, heat or light, and forming a new solid.
Identify the reactants and products in the equation O2 + 2H2 → 2H2O.
Reactants: O2 and H2
Product: H2O.
What distinguishes a chemical reaction from a physical reaction?
A chemical reaction creates new substances, while a physical reaction only changes the form, like ice melting into water.
Explain the law of conservation of mass.
Matter cannot be created or destroyed; the total mass stays the same during a chemical reaction.
Can we create matter?
No, we can only rearrange it into different forms.
