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HS PS 1-1 - Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
PS1.A: Structure and Properties of Matter
Each atom has a charged substructure consisting of a nucleus, which is made of protons and neutrons, surrounded by electrons.
The periodic table orders elements horizontally by the number of protons in the atom’s nucleus and places those with similar chemical properties in columns. The repeating patterns of this table reflect patterns of outer electron states.
Trend: Neutral Atoms / Common Ions Formed
Trend: Neutral Atoms / Common Ions Formed
Elements will form ions (charged atoms) when they either gain or lose electrons from their valence (outer shell).
Positive ions = Cations = Same name (i.e. Sodium atom and Sodium ion same name)
Negative ions = Anions = Different name = Fluorine becomes Fluoride ion.
Ions can be predicted based on their column or group.
Column 1: 1+ (+) cations
Column 2: 2+ cations
Column 6: 2- anions
Column 7: 1- (-) anions
Column 8: Will not form ions. They are already have stable valence shells.
Trend: Atomic radii
Trend: Atomic radii
Atomic Radius - measures of the size of an atom, based on the distance from the center of the nucleus to the boundary of the outermost electrons (valence electrons)
Atomic radius decreases from left to right within a period. This is caused by the increase in the number of protons and electrons across a period. One proton has a greater effect than one electron; thus, electrons are pulled towards the nucleus, resulting in a smaller radius.
Atomic radius increases from top to bottom within a group. This is caused by electron shielding.
Questions you should be able to answer when done:
Define the “atomic radius.”
What are the units of measurement for the atomic radius?
How does the atomic radius of different elements change across a period?
How does atomic radius change from top to bottom within a group?
Explain why the atomic radius of hydrogen is so much smaller than the atomic radius of potassium.
Trend: Electronegativity
Trend: Electronegativity
Electronegativity - refers to an atom’s ability to attract the electrons present in a chemical bond, or an atom’s ability to attract electrons when that atom is part of a specific compound.
From left to right across a period of elements, electronegativity increases.
If the valence shell of an atom is less than half full, it requires less energy to lose an electron than to gain one. Conversely, if the valence shell is more than half full, it is easier to pull an electron into the valence shell than to donate one.
From top to bottom down a group, electronegativity decreases.
This is because atomic number increases down a group, and thus there is an increased distance between the valence electrons and nucleus, or a greater atomic radius.
Questions you should be able to answer when done:
Define “electronegativity.”
What are the least electronegative elements?
Why are the electronegativity values of metals generally low?
Describe the trend in electronegativities across the periodic table.
Describe the trends in electronegativities in a group of the periodic table.
What happens if atom A in a bond has much more electronegativity that atom B?
Atomic Radius and Electronegativity.pdf
CK12 Reading - Electronegativity - ASSIGNED THROUGH GOOGLE CLASSROOM
Atomic Radius and EN.wavAtomic Radius / Electronegativity Podcast (Protip: Listen to podcast while reviewing notes)
Trend: Reactivity
Trend: Reactivity
Reactivity - measures how readily a substance undergoes a chemical reaction.
Atoms have one goal in life - to be full! They will gain, lose or share electrons when combining with other elements so that they have a full outer shell, making them stable (but not necessarily neutral)
An elements reactivity is the tendency to gain, lose or share these valence electrons.
The number of electrons in the outermost shell of an atom (valence electrons) determines its reactivity
The trend for metal and non-metals is OPPOSITE.
Non- metals GAIN electrons. (left side of p-table)
Metals LOSE electrons. (right side of p-table)
Questions you should be able to answer when done:
Define “metallic character.”
Define “nonmetallic character.”
Describe the trend in metallic character going down a group.
Describe the trend in nonmetallic character going across the periodic table.
Why does the metallic character increase as you go down a group?
Text Resources
Text Resources
Your Personal Periodic Trends ChatBot
Your Personal Periodic Trends ChatBot
If you had to explain why atoms get bigger as you go down a group, how would you describe it?
Imagine you're a tiny particle near the nucleus of an atom. What changes would you notice as you move outwards to the valence shell?
What do you think happens to an atom's ability to attract electrons as it gets larger? Why?
Why do you think elements in the same group tend to react similarly? Can you think of any real-world examples?
If you were tasked with finding the most reactive metal and nonmetal, where would you look on the periodic table?
What do you think makes fluorine more reactive than chlorine, even though they’re in the same group?
Why do you think metals tend to lose electrons, while nonmetals tend to gain them?
Imagine you are designing a new element. Where would you place it on the periodic table if you wanted it to be highly electronegative?
If you could shrink down to atomic size, what do you think would make it easier or harder to remove an electron from an atom?
What’s your best guess as to why noble gases don’t form compounds easily? How would you explain this to someone who doesn’t know chemistry?
Possible Question Starters:
Explain the trend in atomic radius across periods
How does electronegativity change in a group?
Can you help me understand atomic structure?
What are alkali metals and their properties?
Can you quiz me on trends in atomic radii?
Can you ask me some questions about properties of families/groups?
How does the atomic radius change as you move down a group or across a period on the periodic table?
What patterns can you identify in electronegativity across different groups and periods?
How does the reactivity of metals and nonmetals differ across periods and down groups?
Why do noble gases tend to be less reactive compared to other groups?
How does the number of valence electrons affect an element’s chemical reactivity?
Why does the atomic radius increase when moving down a group but decrease across a period?
How do elements within the same group compare in terms of their electron configurations?
What is the relationship between an element’s position on the periodic table and its ionization energy?
How would you explain the trend in metallic character across periods and down groups?
Why do elements in the halogen group become less reactive as you move down the group?
HS-PS1-1 Rubric
HS-PS1-1 Rubric
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