dujail
The Kurds. The Kurds in Iraq are still under attack from Turkey and Iran.
Sunni Arabs
Saddam Hussein was a horrible person. He attacked nearly everyone who opposed his reign or was from outside of his Sunni Arab ethnic group. Saddam Hussein repressed the Sunni, Shiite, and Yazidi Kurds because they sought to have an independent country and gain equality with Arab Iraqis. Saddam Hussein preferred to maintain a discriminatory and prejudicial system.
george w. bush
Group 18
The Kurds (an ethnic group) and the Shiite Arabs (a religious group) were the most prominent of Saddam Hussein's ethnic/religious adversaries, but many smaller groups like the Marsh Arabs, Assyrians, Chaldeans, Turcomans (Iraqi Turkmen), the Jews, the Yazidis, Catholics, etc. were also targeted by Saddam Hussein.
The elements that are almost completely unreactive are the noble gases in group 18.
The two pieces of the question do not fit together. The "religious group comprises a majority of Iraqi population" was the Twelver Shiite Muslims and the "religious group that held political authority and economic power under the Saddam Hussein" was the Sunni Muslims. The Sunnis were an empowered minority while the Shiites were a powerless majority.
Like any group of people engaging in genocide, the Nazis did not consider the Holocaust victims to be "their own people". In order to engage in this type of killing of a group of people, it is necessary to cast them as different, and indeed, less than human. This can be seen in the extermination of native populations in America, recent mass murders in Rwanda and Darfur, the killings of Kurds in Iraq in the 1980s, etc. So when President George Bush was making the argument that Saddam Hussein "gassed his own people" (referring to the Kurds), it's worth noting that while that was technically accurate, Hussein did not consider the Kurds to be "his own people". In the same way, Nazis did not consider the victims of their own mass murders to be "their own people".
These groups are 17 and 18.
group 18 has completely filled electronic configuration and hence are stable. group 1 and group 2 have 1 and 2 electrons respectively in their valence shells and needs to lose these to attain completely filled electronic configuration. hence they are reactive.
Watchtower encourages Jehovah's Witnesses (as it is written in Bible as Jesus asked Christians to do) to go and to talk with people, share their knowledge, share their viewpoints. If they wanted to create a mentally completely isolated group, they would prohibit door-to-door preaching and talking with other people. But they don't do that, because they love Jehovah, love Christ and love their neighbors.