4-3 notes elements, isotopes, & ions chapter 4, lesson 3
TRANSCRIPT
4-3 NotesElements, Isotopes, & Ions
Chapter 4, Lesson 3
Atomic Number and the Periodic Table
An element is a pure substance that can be identified by the number of protons in its nucleus.
6C
Carbon12.01
6 protons
Atomic Number and the Periodic Table
Each atom of a particular element always has the same number of protons.
6C
Carbon12.01
6 protons
Atomic Number and the Periodic Table
The atomic number tells you the element’s number of protons.
6C
Carbon12.01
6 protons
Atomic Number and the Periodic Table
Elements are organized onto a chart called the Periodic Table of the Elements.
Atomic Number and the Periodic Table
Elements are arranged horizontally (left to right) by increasing atomic number.
Atomic Number and the Periodic Table
They are arranged vertically in columns of elements with similar chemical properties.
Atomic Number and the Periodic Table
Elements in the periodic table are mostly metals, but also include nonmetals and semimetals (or metalloids).
Isotopes – Different Numbers of NeutronsThe number of protons for an element can NOT
change. The number of neutrons CAN change.
Isotopes
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Isotopes – Different Numbers of NeutronsAtoms of the same element that contain
different numbers of neutrons are called isotopes.
Isotopes – Different Numbers of Neutrons
The atomic mass of an atom is a decimal, and it represents the average mass of all isotopes of an element.
6C
Carbon12.01 Atomic Mass
Isotopes – Different Numbers of Neutrons
The mass number of an atom is the total number of neutrons plus protons in the atom. You find it by rounding the atomic mass to a whole number.
6C
Carbon12.01
Atomic Mass Number
rounds DOWN to 12
Atomic Mass
Isotopes – Different Numbers of Neutrons
To calculate the number of neutrons, subtract the atomic number from the mass number.
6C
Carbon12.01
Atomic Mass Number
Atomic Number
12
6
6
Isotopes – Different Numbers of NeutronsIsotopes with more neutrons are heavier than
isotopes with fewer neutrons.
Isotopes – Different Numbers of NeutronsThe isotope Carbon-14: 14 is the mass number
(# of protons + # of neutrons).
Isotopes – Different Numbers of NeutronsSome isotopes are radioactive, and radioactive
decay occurs when an unstable nucleus changes into another nucleus by emitting one or more particles and energy.
All elements with atomic numbers higher than 92 are synthetic & radioactive elements and exist only because scientists create them.
Isotopes – Different Numbers of NeutronsAn isotope of americium is shown releasing an
alpha particle.After losing two protons, americium becomes
the element neptunium.
Isotopes – Different Numbers of Neutrons
Isotopes – Different Numbers of NeutronsThe half-life of a radioactive element is the time
it takes to decay to half its original mass.
Some elements have a half life of millions of years, some less than a second.
• Half-life of a Carbon-14 isotope is 5730 years.
Isotopes – Different Numbers of Neutrons
Hydrogen has three isotopes, called: protium, deuterium , and tritium.
Isotopes – Different Numbers of Neutrons
Hydrogen has three isotopes, called: protium, deuterium , and tritium.
Isotopes – Different Numbers of Neutrons
Hydrogen has three isotopes, called: protium, deuterium , and tritium.
Isotopes – Different Numbers of Neutrons
Hydrogen has three isotopes, called: protium, deuterium , and tritium.
Isotopes – Different Numbers of Neutrons
Hydrogen has three isotopes, called: protium, deuterium , and tritium.
Ions – Gaining or Losing Electrons
The number of electrons CAN change.If this happens, the atom no longer is
overall neutral.The atom does not have the same
number of protons (+) and electrons (-)An ion is an atom that no longer is neutral
because it has gained or lost electrons.
Ions – Gaining or Losing Electrons
Ions – Gaining or Losing Electrons
When it loses an electron, it has more protons (positives) than electrons (negatives), and has an overall positive charge.
An atom with a positive charge is called a positive ion.
Ions – Gaining or Losing Electrons
When it gains an electron, it has more electrons (negatives) than protons (positives).
An atom with a negative charge is called a negative ion.
Ions – Gaining or Losing Electrons
Positive ions and negative ions attract each other and form compounds.
+ -
new element
molecule
isotope
ion
The carbon element has several isotopes. How is carbon-14 different from carbon-13?
A Carbon-14 has a positive charge.
B Carbon-13 has a positive charge.
C Carbon-14 has one more neutron than carbon-13.
D Carbon-14 has one less neutron than carbon-13.
1. A
2. B
3. C
4. D
What is the number of protons in an element called?
A isotope
B atomic number
C atomic mass
D radiotope
4.3 Elements, Isotopes, and Ions—How Atoms Differ
1. A
2. B
3. C
4. D
How does a neutral atom become a negative ion of the same element?
A It gains a proton.
B It loses a proton.
C It loses an electron.
D It gains an electron.
4.3 Elements, Isotopes, and Ions—How Atoms Differ
1. A
2. B
3. C
4. D
An atom contains 10 electrons, 11 protons, and 11 neutrons. What is the charge on the atom?
A 1−
B 1+
C 2−
D 2+
Elements with the same number of protons but differing numbers of neutrons are called ____.
A ions
B electrons
C tritium
D isotopes
The atomic mass of an atom is equal to ____.
A the number of protons
B the number of neutrons
C the number of protons and neutrons
D the number of electrons and protons
SCI 3.a
The atomic number of carbon is 6. Carbon-14 contains ____.
A 7 protons and 7 neutrons
B 6 protons and 8 neutrons
C 8 protons and 6 neutrons
D 6 protons and 6 neutrons
SCI 7.b
What happens when an atom gains a negative charge?
A The atom gains an electron.
B The atom gains a proton.
C The atom loses an electron.
D The atom loses a proton.
SCI 3.a
How long would an 80 g sample of barium-131 take to decay to 5 g if the half-life is 12 days?
A 12 days
B 6 days
C 36 days
D 48 days
7.2 Isotopes and Radioactivity
1. A
2. B
3. C
4. D
80 grams
40 grams
20 grams
10 grams
5 grams
12 days
12 days
12 days
12 days
24 days
36 days
48 days
How long would an 80 g sample of barium-131 take to decay to 5 g if the half-life is 12 days?
A 12 days
B 6 days
C 36 days
D 48 days
7.2 Isotopes and Radioactivity
1. A
2. B
3. C
4. D