Chapter 2 Pt. 1 Flashcards
What is chemistry?
the branch of science concerned with the composition and properties of substances, including the stuff our bodies are built from
What is matter?
anything that takes up space and has mass
How is matter measured?
often in grams or kilograms (or ounces and pounds)
What are the three states of matter?
solids, liquids, and gases
matter is made up of ______
atoms
What are atoms?
units of matter that cannot be broken down into simpler substances by ordinary chemical means
In an atom; the ________ is at it’s center, and a surrounding spherical “cloud” of ________
nucleus
electrons
Electrons move around the _______ and occur at certain energy levels called _____
nucleus
shells
What is a shell?
3 dimensional spaces
How many electrons does the shell closest to the nucleus have?
2 electrons
How many electrons does the shell second closest to the nucleus have?
8 electrons
Electrons with the most energy are found ________ from the nucleus
farthest
What type of charge do electrons have?
negative
Atoms with more than ___ electrons have additional shells
10
What does the number of electrons in the outermost shell determine?
an atom’s chemical properties
Electrons with the most energy are found ________ from the nucleus
farthest
What type of charge does an electron, neutron, and proton have?
electron=negative
neutron=neutral
proton=positive
Most atoms have the same number of _______ and ________
protons
electrons
What is an element?
a pure form of matter containing only one kind of atom
What is an atomic number?
the number of protons in the atom’s nucleus
What is the approximate mass of protons and neutrons?
1 atomic mass unit
What is the approximate mass of electrons?
0
The ______ _____ for any _____= the number of protons + the number of neutrons
atomic mass
atom
The atomic mass for any atom= the number of _______ + the number of neutrons
protons
The atomic mass for any atom= the number of protons + the number of ________
neutrons
What is the difference between isotopes and radioisotopes?
isotopes- atoms that have the same number of protons but differ in the number of neutrons (some elements have both stable & unstable isotopes)
radioisotopes- unstable, radiation-emitting isotopes
What are some examples of radioisotopes?
- radio waves
- light
- heat
- the excess energy or particles given off by unstable isotopes as they break down
How can radiation be dangerous?
- absorption can lead to damage of organs (i.e. skin) and development of some cancers
- it may alter the hereditary material in the cells of the reproduction system
How can radiation be useful?
medical professionals use it for: diagnosis and therapy, and killing cancer cells
What is a compound?
2 or more elements combining to form a new chemical substance
How are atoms (or ions) held together in a compound?
by chemical bonds
When atoms form bonds they _____, _____, or ______ the electrons in their outermost shell
lose
gain
share
When atoms form bonds they lose, gain, or share the electrons in their ________ shell
outermost
What are the 2 types of chemical bonds found in compounds?
(1) Covalent Bond
(2) Ionic Bond
Which type of chemical bond is this:
forms when 2 or more atoms share electrons in their outer shells
Covalent Bond
Which type of chemical bond is this:
“opposites attract”
Ionic Bond
What is a molecule?
a chemical structure held together by covalent bonds
What are the different types of covalent bonds?
single covalent bond- a bond in which a single pair of electrons is shared
double (or triple) covalent bonds- two atoms share two (or three pairs) of electrons
How are covalent bonds represented in a structural formula?
single covalent bond= single line
double covalent bond (or two pairs of shared elements)=double lines
What is an ion?
an atom or group of atoms that carries either a positive (+) or a negative (-)
How do ions form?
the tendency of atoms to attain a complete outermost shell
Electrical charges, in ionic bonds, result from the _______ (not sharing) of ________ between atoms
transfer
electrons
