Phase Changes
The phase change from solid to liquid
What is melting?
Name two physical properties
density, color, malleability, hardness, elasticity, boiling point, conductivity, viscosity, transparency, and brittleness are all answers that are accepted
This type of change does NOT create a new substance, such as cutting paper or breaking glass.
What is a physical change?
What is a molecule
The smallest chemical unit. Made up of atoms.
One example of a pure substance
Any element on the periodic table
Is energy added or taken away during condensation?
Taken away
This property of matter describes how well a material allows heat or electricity to pass through it.
What is Conductivity?
This type of change results in the formation of one or more new substances with different properties.
What is a chemical change?
Where are all of the elements found?
What is the periodic table.
This subatomic particle has a negative charge and moves around the nucleus.
What is an electron?
Solid to gas phase change
What is sublimation?
If an object has a density of 0.89, will it float or sink in water?
Float - water's density is 1 g/cm3
What are two signs of a chemical change?
changing to a new color, forming bubbles, energy change, formation of a precipitate, new odor, light/energy released
Is O2 an element, compound, or molecule?
Molecule.
Rows on the periodic table are called this and tell how many energy levels an atom has.
What are periods?
Do the atoms in a substance move faster or slower during evaporation?
Faster - liquid to gas
Name three chemical properties
flammability, toxicity, acidity, reactivity, and heat of combustion are all accepted answers
CH4 + 2O2 = CO2 + 2H2O
Is this a physical or chemical change, why?
What is a chemical change because you have new products (substances) in the end?
What are the differences between compounds, elements, and molecules?
Compounds are 2 or more elements chemically combined
Elements cannot be broken down into smaller states
Molecules are made up of both compounds and elements (all compounds are molecules, but not all molecules are compounds)
This number on the periodic table tells you how many protons are in an atom.
What is the atomic number?
During a phase change, such as melting or boiling, this property stays constant even though energy is still being added to the substance.
What is temperature?
A student observes an ice cube melting, a piece of wood burning, and a piece of paper being torn. Which observation is an example of a chemical change, and why?
What is the wood burning because it produces a new substance (ash and gases)?
A substance is heated. The particles move faster and spread out, but no new types of particles appear. What is the change and why?
What is a physical change because only particle motion changes, not identity?
What differentiates pure substances and mixtures?
Pure substances always have the exact same composition, whereas mixtures are two or more pure substances combined together
Columns on the periodic table are called this and elements in the same column have similar properties because they have the same number of these.
What are groups (or families), and valence electrons?