Question

section 3.1 what are elements?
in your textbook, read about elements and atomic structure.
use each of the terms below just once to complete the passage.
atom electrons element neutrons nucleus protons
a(n) (1)________is a substance that cannot be broken down
into simpler substances. a(n) (2)________is the smallest particle
of matter having all that elements characteristics. it is made up of smaller particles.
the (3)________is made up of protons and neutrons. small
particles that have mass and positive electrical charges are (4)________.
particles that have about the same mass as protons, but that are electrically neutral are
(5)________. surrounding the nucleus of an atom are tiny particles called
(6)________, which have little mass, but have negative electrical charges
that are exactly the same magnitude as the positive charges of protons.
in your textbook, read about atomic structure and isotopes.
complete each statement.

1. the number of protons in an atoms nucleus is the________.
2. when atoms of the same element have different mass numbers, they are known

as________of that element.

1. the spontaneous process through which unstable nuclei emit radiation is

called________.

1. a(n)________represents the area in an atom where an electron is

most likely to be found.

1. the outermost electrons of an atom are called________.
2. the combined number of protons and neutrons is the________.
3. the________is the average of the mass numbers of the isotopes of

an element.

Explanation:

1. An element is a substance that cannot be broken down into simpler substances.
2. An atom is the smallest particle of matter having all that element's characteristics.
3. The nucleus is made up of protons and neutrons.
4. Protons are small particles that have mass and positive electrical charges.
5. Neutrons have about the same mass as protons but are electrically neutral.
6. Electrons surround the nucleus, have little mass, and negative charges equal in magnitude to proton charges.
7. The number of protons in an atom's nucleus is the atomic number.
8. Atoms of the same element with different mass numbers are isotopes.
9. The spontaneous process of unstable nuclei emitting radiation is radioactivity.
10. An orbital represents the area where an electron is most likely found.
11. The outermost electrons of an atom are valence electrons.
12. The combined number of protons and neutrons is the mass number.
13. The atomic mass is the average of the mass numbers of the isotopes of an element.

Answer:

1. element
2. atom
3. nucleus
4. protons
5. neutrons
6. electrons
7. atomic number
8. isotopes
9. radioactivity
10. orbital
11. valence electrons
12. mass number
13. atomic mass