Foundations of Science
Explain the proper technique for smelling a chemical in a lab setting.
what is wafting
is H2O an element or a compound
Define a physical property and provide two examples.
physical property is a characteristic of a substance that can be observed or measured without changing its chemical identity.
ex. boiling point
ex. freezing point
What does the atomic number of an element represent?
what is the number of protons in the atom's nucleus
How many significant figures are in the number 102.040 L
6
Why should you always wear safety goggles when working with any chemicals or heat sources?
to protect your eyes from splashes, fumes, and burns
what is an example of a homogenous mixture and a heterogenous mixture
Homogenous= salt dissolved in water
Heterogenous= trail mix
Define a chemical property and provide two examples
chemical property describes a substance's ability to change into a new substance during a chemical reaction
ex. reactivity
ex. flammibility
what is J.J. Thompson's atom model?
what is the plum pudding model
How many meters are in 3.5 kilometers?
3500 meters
What are the main steps of the Scientific Method?
what is state problem, research, form a hypothesis, design experiment, analyze data, state conclusion, communicate results
what is the difference between a pure substance and a mixture
a pure substance is made up of only one kind of particle and a mixture consists of different kinds of elements
Is dissolving salt in water a physical or chemical change?
what is a physical change
Define a valence electron
A valence electron is an electron in the outermost shell of an atom that can form chemical bonds with other atoms
A student determines the boiling point of a liquid to be 95.0∘C. If the accepted value is 100.0∘C, calculate the percent error
5.0%
What is the standard SI unit for measuring mass, and what common lab equipment is used to measure it?
what is grams and a balence
describe the arrangement and movement of particles in a gas state compared to a solid state
In a gas, particles are far apart and move randomly and quickly, while in a solid, particles are tightly packed in fixed positions and can only vibrate
why is the condensation of water vapor into liquid water is considered a physical change.
it involves a change in the state of matter without changing the chemical composition of water
Define a cation and an anion
A cation is a positively charged ion, while an anion is a negatively charged ion
A substance has a mass of 27.0 g and occupies a volume of 3.0 cm3. Calculate its density
9g/cm^3
What is the definition of chemistry?
what is the study of matter, what it is made of, and how it interacts with other matter
What is the most common method used to separate the components of a homogeneous mixture
what is distillation
Why is boiling point considered a physical property?
it is a characteristic that can be observed without changing a substance's chemical identity.
Define isotope and explain how isotopes of the same element are different from one another.
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This difference in neutrons gives each isotope a different atomic mass, and can lead to some isotopes being unstable while others are stable.
A sample initially contains 40.0 g of a radioactive substance. If the half-life is 5 years, how much of the substance will remain after 15 years
5g