Pure Substances and Mixtures (S8P1.a)
This is matter made of only one type of atom.
What is an element?
This state of matter has a definite shape and definite volume.
What is a solid?
This physical property describes how much matter is in an object.
What is mass?
This type of property describes how easily a substance burns.
What is combustibility?
This is the smallest unit of an element that retains the properties of that element.
What is an atom?
This pure substance contains two or more different elements chemically combined.
What is a compound?
This state of matter has a definite volume but takes the shape of its container.
What is a liquid?
This property describes the amount of mass in a given volume.
What is density?
This type of property describes how a substance reacts with another substance.
What is reactivity?
These positively charged particles are found in an atom's nucleus.
What are protons?
This type of mixture has a uniform composition throughout, like salt water.
What is a homogeneous mixture?
In this state of matter, particles move freely and spread out to fill their container.
What is a gas?
This physical property identifies the temperature at which a solid becomes a liquid.
What is melting point?
Burning wood is an example of this type of change because new substances are formed.
What is a chemical change?
These particles have a negative charge and move around the nucleus.
What are electrons?
This type of mixture has visibly different parts, like a salad.
What is a heterogeneous mixture?
When thermal energy is added to a substance, the particles generally move in this way.
What is faster?
A scientist measures the temperature at which water changes from a liquid to a gas. What property is being investigated?
What is boiling point?
A student mixes two clear liquids and observes bubbles forming. This may be evidence of what type of change?
What is a chemical change?
This number on the periodic table tells you how many protons an atom has.
What is the atomic number?
Explain why salt water is a mixture rather than a compound.
Because the salt and water are physically combined, not chemically bonded, and can be separated by physical methods.
A substance changes from a gas into a liquid as thermal energy is removed. Identify the change and explain what happens to particle motion.
What is condensation? Particles lose energy, slow down, and move closer together.
Two objects have the same volume, but Object A has twice the mass of Object B. Which object has greater density, and why?
Object A, because it has more mass in the same volume.
A student cuts a piece of paper into smaller pieces. Explain why this is a physical change rather than a chemical change.
Because the paper's size and shape change, but its chemical composition remains the same.
An atom has 8 protons, 8 neutrons, and 8 electrons. Identify the element and explain how you know.
What is oxygen? Its atomic number is 8, meaning it has 8 protons.