An electron can be removed from an atom if enough energy is supplied. This is called ionization energy.
Using A as a symbol for an atom of any element, the process can be expressed as follows:
A + energy → A⁺  +  e-
To compare the ease with which atoms of different elements give up electrons, chemists compare ionization energies. (To avoid the influence of nearby atoms, measurements of ionization energies are made on isolated atoms in the gas phase.)
What is ionization energy?

• Energy required to remove an
    electron from a neutral atom
• energy to gain an electron

Ionization energies are measured in kJ/mol.
What do you think kJ/mol is the abbreviation for?

• kilojoules/mole
• kilojolts/mole
• kilojoules/mile
• kilojoules/minute

The trend of ionization energy seen on the periodic table is increase across a period and up a column. As seen in the image. Which would have a greater ionization energy, K or Na?

• K
• Na

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NGSS.HS-PS1-1

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Greater ionization energy ? Li  or  Be

• Li
• Be

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NGSS.HS-PS1-1

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Greater ionization energy? Na  or  K

• Na
• K

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NGSS.HS-PS1-1

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Which direction does energy flow?

• from hot to cold
• from cold to hot
• from lower kinetic energy to higher kinetic energy 
• every direction

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NGSS.HS-PS3-4

The SI unit of heat and energy is the __________.

• calorie
• heat
• joule
• watt

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NGSS.HS-PS3-4

ΔH value in an endothermic reaction is a positive number.

• True
• False

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NGSS.HS-PS1-4

At the end of chemical reactions, what is the total mass of the reactants compared to the total mass of the products?

• the product is doubled
• the product is half the mass of the reactants
• the mass is the same
• the mass changes depending on the reaction

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NGSS.HS-PS1-7

Which one is a compound?

• Co
• Br
• Fe
• CO

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NGSS.MS-PS1-1