Periodic Trends
From top to bottom on the periodic table, ______________ increases
Atomic Radius
A requirement that a design must meet to be successful is called a ______.
Criterion
What subatomic particle has a positive charge?
Proton
A scientist examines three samples:
Sample B and Sample C
A substance changes color and forms a new material. What type of change is most likely occurring?
Chemical change
Which element has the larger atomic radius, sodium (Na) or Chlorine (Cl)?
Sodium (Na)
A limit such as time, cost, or materials is called a ______.
Constraint
What does an element's atomic number tell you?
The number of protons
Two students disagree about orange juice with pulp. One says it is homogeneous because it's mostly liquid. The other says it is heterogeneous. Who is correct and why?
The second student is correct because the pulp creates visibly different parts in the mixture
Which is evidence of a chemical change? A. Melting B. Boiling C. Gas production D. Crushing
Gas production
Two elements are in the same group. Element A has a larger atomic radius than Element B. Which element would likely have the lower electronegativity?
Element A
A student is designing a bicycle helmet. The helmet must protect the rider during a fall. __________
Criterion
A student says, "The mass number of an atom is found by adding the protons and electrons." Explain why the student is incorrect.
Mass number equals protons + neutrons, not electrons
Compare a cup of salt water and a bowl of vegetable soup. Which is homogeneous and which is heterogeneous? Explain why.
Salt water is homogeneous because the substances are evenly distributed. Vegetable soup is heterogeneous because different components can be seen.
A student says, "Any change that can be seen is a chemical change." Explain why this statement is incorrect.
Many visible changes, such as melting, cutting, or crushing, are physical changes because no new substance forms
Which element would attract bonding electrons most strongly: S, O, Se, or Te?
Oxygen (O)
Which design is closer to being successful and why?
Design A because it meets the intended purpose. The constraint can potentially be adjusted, but the design must first accomplish its function.
Scientists observed that:
Using this evidence, explain what scientists concluded about the structure of the atom.
Scientists concluded that atoms are mostly empty space because most particles passed through.
A mixture appears uniform to the naked eye, but under a microscope different substances can be seen. How should it be classified?
Heterogeneous mixture
A student leaves a bicycle outside. Weeks later, orange rust appears on the metal. What evidence supports that a chemical change occurred?
Rust is a new substance formed from iron and oxygen?
Fluorine is known for having the highest value of which periodic trend?
Electronegativity
A track team wants a starting block design that:
Classify each statement as either a criterion or a constraint.
An atom has 17 protons, 18 neutrons, and 17 electrons. If the atom loses one electron, what changes and what stays the same?
A sports drink contains water, sugar, flavoring, and coloring that are evenly mixed. What type of mixture is it?
Homogeneous mixture
A student makes the following observations:
Classify each as a physical or chemical change and use evidence to justify your answers.